Harvey vs CoCounsel Legal: how they compare in 2026
CoCounsel Legal and Harvey now both sell agentic legal AI, so the real difference is what each one reasons from and where the work happens. CoCounsel Legal plans a matter step by step from Westlaw, Practical Law and the firm's own files, and shows its reasoning as it goes. It adds Westlaw Brief Builder and tabular review of up to 10,000 documents against 100 questions. It suits a buyer whose answers need licensed authority behind every citation, and it is sold in plans bundled with Westlaw and Practical Law. Harvey routes work across its own agents, Vault, Knowledge and Spaces, a shared workspace where a firm, its clients and other counsel on the matter collaborate behind ethical walls. Command Center shows who uses it, on what work, against comparable organizations. The fit is a large firm or legal department that wants one platform across practices and offices, and more than 80 AmLaw 100 firms already use it. Harvey's prices come only through a sales conversation, while CoCounsel shows its plan structure. Both hold SOC 2 and ISO 42001 certification, so a security review is unlikely to decide between them.
At a glance
All 15 axes, side by side
The same grid applied to every vendor in the index, graded from public sources. Hover a grade to see what the letter means on that axis.
AI Centrality
How much of the product is actually AI. Whether the machine learning is the mechanism the buyer is paying for or a feature layered onto conventional software, and whether the vendor is specific about which is which.
Agents, Vault review tables, Knowledge research, Contract Intelligence review, Intake triage and Horizon Scanning all produce their output with language models. No document management or workflow system sits underneath that a firm would buy on its own. Vault stores matter documents, and its purpose is extraction, comparison and reporting across them.
The artificial intelligence is the product. CoCounsel Legal exists only as a generative and agentic layer, rebuilt in 2026 on an agent framework so it plans, reasons and executes multi step legal work. Remove the models and there is no product, only the underlying Westlaw and Practical Law content, which the parent sells separately as its own products.
Citation Accuracy and Hallucination Disclosure
Whether the vendor publishes measured accuracy on citations and assertions, grounds output to primary sources, and says plainly what its system does when it does not know. Legal has a documented public record of fabricated citations reaching filed briefs, so an untested claim of accuracy is not evidence.
In the February 2025 Vals Legal AI Report, a third party benchmark set against a lawyer baseline, Harvey Assistant was tested on six tasks. Its results ranged from 65.0 to 94.8 percent, and it beat the lawyer baseline on five. Document question answering reached 94.8 percent, 24.7 points above the baseline, with responses under a minute. Answers on scanned and badly formatted court transcripts reached 77.8 percent, 24.1 points above it. That study measured task accuracy rather than citation validity, and Harvey did not enter the later Vals study of citation authority. BigLaw Bench, Harvey's own benchmark, publishes its task categories and judging criteria on a public repository, with hallucination and source results by model. It defines a hallucination as a factual claim that a source of truth can disprove and tracks reasoning errors apart. Harvey reports that its systems hallucinate less often than the foundation models on legal tasks while giving longer answers. Every agent claim links to the source passage behind it, and the full BigLaw Bench dataset is available on request.
Grounding is described rather than asserted. The research agent identifies key legal concepts, selects Westlaw tools including KeyCite, the Key Number System and annotated statutes, runs multiple search cycles and synthesizes a structured result. Output grounds to primary authority the user can open, with inline citations, a Sources tab with direct links and highlighted excerpts, and KeyCite validity flags shown with the authority. A citation level verification feature, Deep Research Verify, is published, and prompting guardrails restrict output to content validated by people rather than the open internet. Measurement is independent. CoCounsel took part in the February 2025 Vals Legal AI Report, a third party benchmark against a measured lawyer baseline, scoring between 73.2 and 89.6 percent across four tasks with a 79.5 percent average, each task more than 10 points above the lawyer baseline. The vendor also publishes CoCounsel Bench, under which attorneys reviewed 50 complex tasks of about six lawyer hours each and judged the product's response stronger than the expert reference answer on nearly 40 percent. The 2025 study measured task accuracy rather than citation validity or hallucination rate, and the vendor did not take part in the later Vals study on citation authoritativeness.
Autonomy and Oversight Model
What the system decides on its own, what a lawyer must approve, and whether the vendor documents where the review point sits. A tool that drafts under review and a tool that files without one are different products and different risks.
Agents show their plan before they run, so a lawyer can adjust the scope and approve the work before Harvey begins. While an agent works, Harvey brings the lawyer back in when a judgment call is needed, logs every step and cites a source for every claim. Intake applies routing rules the legal team defines to send each request to an approved agent, to Contract Intelligence or to a lawyer. Reports and reviews can run on a schedule, and admins govern access through roles and workspace permissions. The point at which an agent stops on its own, and what Harvey commits to when an agent's work is wrong, are not stated.
A real published commitment with documented review surfaces, without the full control structure. The vendor states that its AI is built with human oversight at its core and publishes a Fiduciary-Grade AI framework built around transparency and accountability. The product is described as showing its plan before executing: it interprets a request, builds a plan specific to the matter, and returns work product with traceable citations the user can open and check. Not located: the threshold at which an agent stops and returns to a lawyer, and what the vendor commits to when an agent is wrong. The August 2026 shift from structured skills to a fully agentic experience makes the missing threshold more material than it would have been a year ago.
Operational and Outcome Evidence
Named, dated evidence that the product works in production at real firms or legal departments. Case studies with figures and identified customers count. Unattributed testimonials and launch announcements do not.
Customer stories name the firm and give figures. Reed Smith, with about 1,800 lawyers in 34 offices, reports 700 Harvey users a day, 1,400 a month and AI certification for every associate. Repsol's legal division started a pilot in January 2024 with 50 lawyers in 12 jurisdictions and reports cutting the time on one process by more than 90%. CMS reports 95% adoption. Other named customers include A&O Shearman, Gleiss Lutz, Cuatrecasas, Macfarlanes, KKR, PwC and Deutsche Telekom. The figures are usage counts and time savings as each customer reports them, with no stated method for how they were measured.
Named customers, dated, with figures and a method that can be assessed. The vendor publishes case studies naming Justly Prudent, reporting five times return on investment and a doubling of litigation capacity, and Brinks, on reducing outside counsel spend. It also publishes a commissioned Forrester Total Economic Impact study dated 2026, whose method can be assessed and whose commissioned status is disclosed on the page. Aggregate figures are published with the population stated, including 2,700 corporate customers using the CoCounsel family and a 61 percent reduction in time to draft correspondence.
Privilege and Confidentiality Posture
How client confidences are handled: attorney client privilege and work product treatment, segregation of one client matter from another, whether client data trains any model, and what the vendor commits to in writing rather than in marketing.
Neither Harvey nor its subprocessors may train any AI model on customer content or data, and model providers work under zero data retention. A firm can ask for a bespoke model trained on its own data and used only for that firm. Harvey syncs and enforces the firm's existing ethical wall policies and never creates, modifies or deletes walls, so the walls provider stays the system of record. Workspaces are logically separated, access follows roles, and data is deleted within 30 days of termination. If the law or a court compels disclosure, Harvey gives advance written notice where it is legally permitted. Attorney client privilege and work product are not addressed as such.
Substantive published commitments, with the answer given directly in a published FAQ rather than implied. The vendor states plainly that customer content and prompts are not used to train or improve the product or the underlying models. Third party model partners, including OpenAI and Google, are contractually prohibited from training on customer data, and systemic controls turn off those parties' abuse monitoring so there is no human access to customer data. The vendor also publishes a zero retention API architecture and data residency controls. Attorney client privilege and work product handling are not addressed directly in located material. Segregation by matter is not documented on the vendor's own pages, although the product is built around matters.
UPL and Professional Responsibility Posture
Whether the vendor is clear that it supplies a tool rather than legal advice, who its audience is, and how it addresses unauthorized practice of law, competence and supervision duties, and jurisdiction limits. ABA Formal Opinion 512 is the reference point. Where the advice line is not the duty a product raises, the axis is read through the nearest professional duty it does raise: judicial conduct rules and the reviewing duty for products sold only to courts, and the duty to bill for time actually spent for products that draft time entries.
Output is not legal advice and may contain errors, misstatements or gaps, and the Platform Agreement calls the service a research tool. Harvey sells to lawyers, legal departments and professional services firms, and its agent pages leave the judgment on every task with the lawyer. Access credentials belong to one named user and may not be shared. Nothing addresses competence and supervision duties under professional rules, or the jurisdictions where the product may be used.
The claim is made and the documentation is not published. The product is sold to licensed professionals and distributed to more than 200 law schools and 120,000 law students. The vendor's framing is that the system works at the level of a senior associate under professional supervision. The product page, the AI hub, the trust center and the legal blog were searched. No published position on the advice line, no treatment of competence and supervision duties, and no statement of jurisdiction limits is published. The senior associate framing is a capability claim rather than a professional responsibility position, and for a product marketed to students it is where a position would matter most.
AI Governance and Bias Disclosure
Published governance over model behavior: who owns it inside the vendor, what is tested before release, and what is disclosed about disparate output across matter types, parties, or populations.
ISO/IEC 42001:2023 certification covers Harvey's AI management system, and the Statement of Applicability published with it sets out the controls in scope. Its AIUC-1 certification, an AI security and safety standard, was conducted by Schellman and, in Harvey's account, validates its adversarial testing and AI security program. The trust center adds IRAP attestation, an EU AI Act item and AI Governance, AI Monitoring and AI Overview documents, with an AI Acceptable Use Policy among its policies. An AI Policy dated 26 December 2025 commits to testing the accuracy, reliability and suitability of the AI in the service and to change management for continuing legal compliance. No accountable owner is named, and nothing is published about uneven output across matter types or populations.
A published governance framework with real substance, short of testing results or a named owner. The vendor publishes a named standard it calls Fiduciary-Grade AI with a buying framework attached, describes a dedicated research organization of more than 1,000 specialists, states a figure for annual responsible AI investment, and answers a direct published question on bias: prompting guardrails restrict output to a clearly defined and limited set of human validated content rather than the open internet. That is a stated mechanism, not a principles page. Not located: a named internal owner of model governance, published pre release testing results, or any disclosure of uneven output across matter types, parties or populations. The bias answer describes a content restriction rather than testing for disparate output.
AI Safety and Data Stewardship
Retention, deletion, access control, and what happens to prompts and documents after they are processed. Whether the vendor states its subprocessors and its incident practice, or leaves the buyer to assume.
Customers choose what to upload, set their own retention policies and can delete data at any time. Within 30 days of termination, Harvey deletes remaining customer data and content unless told otherwise, and the DPA extends return or deletion to every subprocessor. Access runs on role based controls, logical workspace separation, SAML SSO, audit logs and IP allow listing. The Subprocessor List, updated 21 September 2026, names each provider with its purpose and location, and subscribers receive at least 30 days' notice of an addition with a right to object. Under the Security Addendum, Harvey notifies the customer of a security incident without undue delay and within 48 hours. It then reports the incident's nature, the investigation and the mitigation, and keeps relevant logs for at least a year.
Substantive published policy covering most of the ground. SOC 2 Type II and ISO 27001 maintained, ISO 42001 certification referenced for the AI management system, a zero retention API architecture published, data residency controls, 24 hour security monitoring and threat detection, corporate identity management integration, and a corporate trust center carrying the information security framework. Not located: a current named subprocessor list for this product, and a stated incident and breach notification practice. The two named model partners are disclosed in the AI FAQ rather than in a maintained subprocessor list, which is the remaining element of the A bar.
AI Liability and Recourse
What the vendor stands behind contractually when its output is wrong. Indemnities, caps, carve outs, insurance, and whether any of it is published or only reachable through a negotiated agreement.
The Platform Agreement, last updated 9 January 2026, sets out what Harvey stands behind. Section 8 indemnifies the customer against third party claims that the service infringes intellectual property. If a claim arises, Harvey may substitute the service, secure a license to continue, or terminate and refund prepaid fees. The indemnity excludes materials Harvey did not provide and output from input the customer knew was likely to infringe. Harvey warrants that the service conforms to its documentation, is delivered in a professional manner and complies with applicable law. It also commits to carry industry standard insurance with insurers rated A- or better by A.M. Best. Total liability is capped at the greater of 12 months of fees or $250,000. Payment, indemnity and claims the law will not let a contract limit, such as gross negligence, sit outside that cap. Data breach and confidentiality claims carry a separate cap of twice 12 months of fees or $500,000. After a security incident, the Security Addendum commits Harvey to an independent forensic investigation at its own cost. The agreement states that output is AI generated and may contain errors.
No published indemnity scope, liability cap, exclusion, warranty on output or insurance position is published for this product. Commercial terms are reached through a negotiated subscription agreement. The Fiduciary-Grade AI framework treats accountability as a design principle rather than saying who bears the loss when output is wrong. A fiduciary framing sits here without a published liability position.
Practice Systems Integration Depth
How deeply the product reaches into the systems legal work already lives in: document management such as iManage and NetDocuments, Word and Outlook, contract lifecycle management, matter management, e-billing, and court filing systems.
Word, Outlook, Teams and SharePoint all run Harvey inside them, and Vault syncs documents from iManage, SharePoint and Google Drive. The iManage connection is a direct OAuth integration with an embedded web extension, and NetDocuments access follows the firm's existing permissions. Intake takes requests from email, Jira, Slack, ServiceNow, iManage, Google Drive and SharePoint and sends updates back to the source channel. Command Center syncs employee profiles through SCIM. Aderant and Ansarada integrations are documented in the trust center, and customers can build their own integrations, including through an MCP connector library. LexisNexis content reaches research through Ask LexisNexis.
Real and documented integrations, short of implementer level depth. Named connections span document management with iManage, NetDocuments and SharePoint, Microsoft 365, the parent's own HighQ collaboration platform and Legal Tracker, contract lifecycle through Icertis, plus DeepJudge, Supio and Smokeball, and a Word add in carrying a personal clause library. An MCP integration lets a lawyer reach the product from a separate AI client without switching platforms, which is a genuinely forward integration surface. Not located: documentation describing what each integration moves, in which direction, and what an administrator must configure.
Deployment Model and Data Residency
Where the software runs and where the data sits. Multi tenant cloud, single tenant, private deployment, on premises, and whether region of residence is a published option or an enterprise conversation.
Microsoft Azure hosts Harvey's cloud environment, with each customer's data logically separated and access set by role. Customers can keep data in region in the EU or Switzerland, the United States or Australia. Customers with localization needs can also have processing in the EU and Switzerland or in Australia, and that commitment extends to Harvey's subprocessors. The Subprocessor List gives each model provider's processing locations. Where Anthropic or Mistral models are not offered in a chosen region, Harvey reaches them through hosting platforms such as AWS Bedrock and Google Vertex. What changes between plans or tiers is not stated.
Deployment is stated clearly with partial residency detail. The vendor publishes data residency controls that keep information within required geographic boundaries, operates a rollout sequenced by country across the United States, Canada, the United Kingdom and Australia, and holds FedRAMP In Process status for the underlying Westlaw and Practical Law products with stated investment toward authorization for this one. Not located: the list of available regions, the tenancy model, what changes between tiers, and where processing happens as distinct from where data is stored.
Security Certifications and Trust Center
Independent attestation a buyer can pull without a sales call: SOC 2, ISO 27001, penetration test summaries, a trust center with current reports and named scope rather than a badge image.
Schellman audits Harvey for SOC 2 Type II and ISO 27001 every year, and the 2026 audit and certification renewal are complete. The trust center also lists ISO 27701, ISO/IEC 42001, AIUC-1, IRAP, TX-RAMP, GDPR, CCPA and an EU AI Act item. It publishes Statements of Applicability for ISO 27001, 27701 and 42001. Schellman, NCC Group and Bishop Fox perform external audits, and third party penetration tests run every year. Reports, the CAIQ v4.0.3, SIG Core and SIG Lite questionnaires and the data flow and network diagrams are released through a self serve access request, with bulk download.
Certification is real and stated, without accessible evidence. SOC 2 Type II and ISO 27001 are stated as maintained, and ISO 42001 is referenced for the AI management system. FedRAMP In Process status is published for Westlaw and Practical Law, with authorization stated as an investment goal for this product, and a corporate trust center publishes the information security management framework. No attestation report, coverage period, audit scope or named auditor is published, and no route to request the reports without a sales conversation is published either. Certifications are stated at the parent company level rather than scoped to this product, which is the distinction a buyer's security team asks about.
Model Supply Chain Disclosure
Which models sit underneath, whose they are, where they run, and whether the vendor commits to telling customers when that changes. A legal buyer inherits every dependency it cannot see.
The Subprocessor List names ten AI providers with their processing locations, among them Microsoft, OpenAI, Google Cloud, Amazon Web Services, Anthropic and Mistral. ElevenLabs supplies voice services, DeepL machine translation, and Baseten and Fireworks.ai further model hosting. Claude and Gemini models run through Amazon Bedrock and Google Vertex AI, as Harvey's subprocessor FAQ explains. Model providers work under zero data retention, with no human review and no training on customer data. Under the DPA, customers who subscribe to the list receive notice at least 30 days before a new subprocessor is added and may object. Which model serves which feature is not stated.
The supply chain is partly disclosed, and specifically. The vendor names Anthropic's Claude Agent SDK as the architecture of the current release, names OpenAI and Google as third party AI partners in a published FAQ, and states the contractual position imposed on them. Not located: which model serves which task, where the models run, a maintained subprocessor list for this product, and any commitment to notify customers before the model supply chain changes. That last gap matters here because the product was rebuilt on a different vendor's agent framework within the past year.
Commercial Transparency
Whether a buyer can learn what this costs without entering a sales process: published rates, the unit being charged, what sits behind an enterprise tier, and what implementation adds.
Fees are set in each customer's order form and invoiced under the Platform Agreement. If an order form is terminated early under the agreement, Harvey refunds a pro rata share of prepaid unused fees. Undisputed late amounts carry a finance charge at the Federal Funds Rate plus 1.5% a year. No rate, plan, tier or unit of charge appears on Harvey's site, and buying starts with a contact sales form.
The shape is visible and the number is not. Tier names and feature splits are published and reachable from the main navigation: CoCounsel Essentials, Westlaw Advantage with CoCounsel Essentials, Practical Law Dynamic Tool Set with CoCounsel Essentials, and CoCounsel Legal. Each has its own plans and pricing page, with variants for law firms, corporations and government. Third party analyses report that the pages run a configurator returning a figure for firms of up to ten attorneys and route larger firms to a sales quote. The configurator could not be checked directly because that subdomain blocks automated access, so no vendor published figure is recorded here; it may say more. The unit of charge is per user per month by third party report rather than vendor statement.
Firm and Practice Coverage
Who the product is actually built for. AmLaw, midlaw, small firm and solo, in house departments, government and courts, and which practice areas are supported rather than merely claimed.
Large law firms, mid sized firms, in house legal departments and professional services firms are the stated buyers. Industry pages cover healthcare and life sciences, technology, energy and utilities, and media, entertainment and telecom. More than 200,000 lawyers at over 3,500 organizations in more than 85 countries use Harvey, including 80% of Am Law 100 firms and five of the Fortune 10. Solutions pages address litigation, transactional work and innovation teams, and research spans legal, regulatory and tax questions across jurisdictions. Firm sizes or practice areas the product is not built for are not stated.
Who the product serves is documented precisely across many segments. Published navigation separates law firms under ten attorneys from firms over ten, and separately addresses corporations, government (including courts, prosecutors, public defenders, city attorneys and law enforcement), and academic use across more than 200 law schools. Practice areas are listed with their own pages, spanning business and commercial, civil litigation, criminal defense, family, labor and employment, mergers and acquisitions and personal injury. The limits are stated structurally rather than in prose: the published table of plans shows exactly which content each plan reaches, so a buyer can see where coverage stops.
The 12 legal signals, side by side
Recorded rather than graded. These are the questions a practitioner has to answer before a tool touches a client matter, and the answers are taken from public material only.
Client Data in Training
Can material a lawyer puts into this product be used to train a model?
Under the Platform Agreement, Harvey will not train any AI model on customer content or customer data, and its subprocessors will not either. The term covers both uploaded documents, which Harvey calls customer data, and the prompts and answers it calls customer content. A firm that asks for it can have a bespoke model trained on its own data and used only for that firm. Harvey may use usage data, such as feature and session statistics, to develop and improve the service, and usage data excludes customer data and content.
A published FAQ answers the question directly and in the negative, stating that user content and prompts are not used to train or improve the product or the underlying models, and that third party AI partners including OpenAI and Google are contractually prohibited from using customer data to train their models. The vendor also states it has established controls to turn off those third parties' abuse monitoring so there is no human access to customer data.
The commitment as located sits on a public FAQ and trust page. No matching term was located in a published customer agreement as of 29 Aug 2026, and the subscription agreement is not published.
Prompt and Output Retention
How long does the product keep what a lawyer typed, and can that be set to zero?
Customers decide what to upload, how long it is kept and whether it can be shared inside the organization, and they can delete data at any time. No default retention period is published. Model providers work under zero data retention, and subprocessors other than cloud storage providers may not retain or log content for human review. After termination, Harvey deletes remaining customer data and content within 30 days unless the customer instructs otherwise.
The vendor publishes a direct answer in a product FAQ. Retention of user content and prompts is customized to the customer, set at the organization account level with the support of a client manager, and the vendor deletes in line with the customer's own retention policy. Users can also delete their content and prompts in the product at any time. That is real customer control over the window. No retention period is published, so the window is whatever the customer negotiates, and setting it runs through a client manager rather than an administrator control the customer operates alone.
The separately published zero retention statement covers the model provider API layer rather than the product's own storage.
Ethical Walls and Matter Segregation
Does retrieval respect the firm’s ethical walls, or can the model read across them?
NetDocuments permissions carry through, so a user sees only the cabinets, matters, folders and files they can already open, and Harvey does not change those permissions. The iManage connection is a direct OAuth integration that respects iManage permissions and ethical walls. Harvey also syncs the firm's own ethical walls provider and blocks walled users from reaching or sharing restricted content.
Searched the product page, the AI hub, the corporate trust center, the legal blog and the published integration announcements on 29 Aug 2026. Integrations with iManage, NetDocuments and SharePoint are named, and corporate identity management integration is stated, but no vendor material was located addressing whether retrieval enforces source system permissions at query time per user, or how ethical walls and matter level segregation are handled.
A third party review refers to granular roles and ethical walls, which is not vendor material and was not treated as evidence.
Third Party Request and Subpoena Notice
If someone subpoenas the vendor for a firm’s data, does the firm hear about it first?
If law or a court order compels Harvey to disclose a customer's confidential information, the Platform Agreement commits it to advance written notice where legally permitted and to help seek confidential treatment. The DPA makes the same commitment for law enforcement requests for personal data. Where the law forbids notice, Harvey seeks a waiver and tells the customer once the prohibition ends. Its Law Enforcement Requests policy sends agencies to the customer first, challenges requests its lawyers consider unlawful and answers foreign requests only through channels such as a Mutual Legal Assistance Treaty. No transparency report is published.
Searched the product page, the AI hub, the corporate trust center and the corporate terms of use on 29 Aug 2026. No clause addressing government or law enforcement requests for customer data was located for this product, and no transparency report was located. Noted for a future reader: a commitment to inform the customer of third party data access requests, audited under ISO 27701, was located on the trust center for a different Thomson Reuters product line, ONESOURCE Pagero. It was not treated as covering this product and does not support a value here.
Primary Law Corpus Provenance
Where does the law in this product come from, and does the vendor have the right to use it?
Knowledge connects questions to legal databases, curated public sources and Harvey's data partners, more than 500 legal sources across jurisdictions. The Subprocessor List names RELX, doing business as LexisNexis, for Ask LexisNexis, and Parallel Web Systems and you.com for web browsing and knowledge sources. Harvey's AI Policy commits it to obtaining the rights and licenses its data sets require. No source list by jurisdiction, license basis per source or update schedule is published.
The source collection is named consistently and prominently. Output is grounded in Westlaw and Practical Law, proprietary databases the vendor owns and sells separately, maintained by more than 1,200 full time attorney editors. Vendor material is explicit that the system draws on this content rather than scraping the public internet. The rights basis is ownership rather than a stated license, and no update cadence or lag for the underlying content was located as of 29 Aug 2026.
Good Law Verification
Does the product tell you when the authority it just cited has been overruled?
Knowledge answers from more than 500 legal sources and draws LexisNexis content through Ask LexisNexis. Harvey does not describe a treatment signal or a later history check on the authorities it returns.
Treatment signals come from KeyCite, the vendor's own named commercial citation service, and appear with the authority. Vendor engineering material states that reports carry inline citations, KeyCite flags and excerpts, and that the research agent uses KeyCite warnings to flag questioned or overruled cases and adjusts its strategy accordingly. Separate vendor material describes the system recognizing red and yellow validity flags and factoring them into its analysis rather than only displaying them.
Refusal and Uncertainty Behavior
What does the product do when the answer is not in the corpus?
BigLaw Bench publishes hallucination rates and explains how Harvey defines and detects hallucinated claims, and agents cite a source for every claim. No setting or behavior is described for declining to answer when Harvey cannot ground a response.
Searched the product page, the AI hub, the legal blog, the engineering blog and the trust center on 29 Aug 2026. Vendor material describes transparent research logs, step by step reasoning, an audit trail and prompting guardrails that restrict output to a defined set of validated content. None of that states what the product does when it cannot ground an answer. No explicit no answer or abstention path was located, and no confidence or grounding score exposed to the user was located either.
Fabricated Citation Record
Does a public court record exist addressing fabricated or hallucinated legal citations in output from this product?
The AI Hallucination Cases database, maintained by Damien Charlotin, records court decisions worldwide that address hallucinated AI content and names the tool involved where known. It lists one matter naming Harvey, Hill v. Foundation Media LLC (S.D.N.Y., No. 25-cv-5947). On 22 September 2026 the court directed defense counsel to say whether AI was used on a brief with two questioned quotations and a citation, and a week later it took no further action.
Harvey is named only in counsel's own letter to the court, which says the brief was prepared with Harvey. No order makes any finding about Harvey or its output. A Galicia High Court order of 7 July 2026 lists Harvey AI among verified legal AI tools while setting a €1,800 fine, again with no finding about the product. Harvey's agreement states that output is AI generated and may contain errors.
A court record exists in which a predecessor brand of this product is mentioned. In Fletcher v. Experian Information Solutions, No. 25-20086, the Fifth Circuit sanctioned appellate counsel $2,500 on 18 Feb 2026 after a reply brief was found to contain 16 fabricated quotations and 5 further misrepresentations of law or fact. The court's findings address counsel's conduct: failure to verify, and evasive and misleading responses to the show cause order, which the court treated as conduct unbecoming under FRAP 46(c).
The products counsel identified as the possible source were named by the court as Casetext and vLex, described as generative AI products. Casetext is the brand Thomson Reuters acquired in 2023 and no longer sells under its own name, and CoCounsel is the surviving product. The court made no finding about either product's own output. The AI Hallucination Cases database maintained by Damien Charlotin was also searched.
Bar Guidance Alignment
Has the vendor engaged in public with the ethics opinions its buyers are bound by?
Harvey's terms call the service a research tool whose output is not legal advice, and the agent pages leave the judgment on each task with the lawyer. No named ethics opinion appears, such as ABA Formal Opinion 512 or a state bar opinion.
Searched the product page, the AI hub, the legal insights hub, the legal blog and the published Fiduciary-Grade AI material on 29 Aug 2026. The vendor publishes a substantial named framework and a buying guide addressed to professional standards in general terms, and markets a responsible AI position to courts and government. No engagement with any named ethics opinion was located, including ABA Formal Opinion 512 and state bar guidance.
Billing and Fee Posture
Does the vendor address what happens to the bill when the work takes an hour instead of six?
ROI calculators for law firms and in house teams sit on Harvey's site, and customer stories report time saved, such as Repsol's. Command Center reports adoption by user, practice group and role. Nothing records AI assisted work per matter for billing, or addresses how a firm bills for that work or discloses it to clients.
Vendor material leads with time compression and quantifies it: a 61 percent reduction in time to draft correspondence, a customer story reporting an hour's task completed in five minutes or less, and a commissioned return on investment study. The product page, the AI hub, the legal blog and the customer stories were searched on 29 Aug 2026. No per matter record of AI assisted work intended for fee purposes was located, and no published guidance on billing, fee or client disclosure treatment. The savings figures are published without anything on the client's side.
Outside Counsel Guideline Readiness
Can a firm get this vendor through a client’s AI clause without a bespoke negotiation?
The trust center offers a Data Processing Addendum, a Business Associate Addendum and a Data Subject Requests item. It adds the CAIQ v4.0.3, SIG Core and SIG Lite questionnaires, data flow and network diagrams, a HIPAA report and a Security Welcome Packet. Sensitive items are released through a self serve request with bulk download. Statements of Applicability for ISO 27001, 27701 and 42001 show what each certification covers.
The public Subprocessor List names every provider with its purpose and location, and subscribers hear of additions 30 days ahead.
A published FAQ names the third party model providers that may process customer content, OpenAI and Google, and states the contractual prohibition imposed on them, with no agreement needed to read it. A corporate trust center publishes the information security framework. Not located as of 29 Aug 2026: a maintained subprocessor list for this product, and any consent or notification pack a firm could forward to its own client.
Court Disclosure Support
If a judge’s standing order requires an AI disclosure, can the product produce one?
Audit logs are a standard enterprise control, agents log every step, and every claim links to the source passage behind it. Command Center reports usage by user and feature. No export brings together the model used, the sources retrieved and the human review for one document.
Several elements of a disclosure record are available and documented. Vendor material states that each research report includes transparent research logs with verifiable citations and step by step reasoning. Sources are hyperlinked with highlighted excerpts in a dedicated tab, and KeyCite validity flags appear with the authority, which together show what was retrieved and its status. Two elements are missing. The model used is not identified per output, since the vendor says the system works across multiple providers, and no export per document covering model, sources and human verification together was located as of 29 Aug 2026.
The questions both sides leave open
Derived from the records above rather than written, so it cannot favor either vendor. Take these into both conversations and ask each side the same question.
- Refusal and Uncertainty Behavior
Which one fits
Choose Harvey if
- The tool has to live inside iManage, NetDocuments or SharePoint on day one. Harvey documents each connection down to what it moves, what an administrator configures and what it does not support.
- You are a large firm running cross border matters and want the vendor that describes that segment first rather than as one branch of a wider professional services product.
- You want an MCP connector library so the platform can be reached from tools your firm already uses, rather than a fixed set of published integrations.
Choose CoCounsel Legal if
- Your research answers need to rest on licensed secondary content rather than on documents you supply, and you want the Practical Law and Westlaw corpus behind the answer instead of retrieval over your own files.
- You need to show a committee that this worked somewhere. CoCounsel's case studies name the customer, carry a figure and sit alongside a commissioned study with a published method.
- Your buying group is not a large firm. CoCounsel separately addresses firms under ten attorneys, corporations and academic use, and its government coverage includes prosecutors and public defenders.
In summary
Harvey
Harvey is an enterprise legal AI platform for law firms, in house legal departments and professional services firms, built around Agents, Vault, Knowledge, Spaces and Contract Intelligence. Its help articles describe each iManage, NetDocuments, SharePoint and Microsoft integration down to what it moves and what an administrator configures. According to the AI Legal Index, Harvey took part in the 2025 Vals Legal AI Report, bars model providers from training on customer data and enforces zero data retention. It sells through its sales team with no published price.
CoCounsel Legal
CoCounsel Legal is Thomson Reuters' legal AI product, grounded in Westlaw and Practical Law and descended from Casetext, which Thomson Reuters acquired in 2023. It plans multistep legal work, drafts with Westlaw Brief Builder and runs tabular review across large document sets. According to the AI Legal Index, CoCounsel's FAQ states that customer content and prompts do not train the product or the underlying models. Third party model partners are contractually barred from training on customer data, and the product is sold in plans bundled with Westlaw and Practical Law.
Questions buyers ask
Is Harvey better than CoCounsel?
They suit different buyers. CoCounsel Legal reasons from Westlaw and Practical Law content and suits teams whose answers need licensed authority behind each citation. Harvey runs agents, document vaults and shared Spaces across practices and offices, and suits a firm that wants one platform for many kinds of work. From the AI Legal Index, based on each vendor's own published materials as of August 30, 2026. No vendor pays for placement.
Which one integrates more deeply with iManage and NetDocuments?
Harvey's help articles describe what each integration moves, in which direction and what an administrator configures, and its iManage connection uses OAuth with an embedded web extension. CoCounsel connects to iManage, NetDocuments, SharePoint, Microsoft 365, HighQ and Icertis. From the AI Legal Index, based on each vendor's own published materials as of August 30, 2026. No vendor pays for placement.
Do Harvey or CoCounsel train their models on client data?
Both say no, at the model provider layer as well as their own. Harvey's Platform Agreement bars Harvey and its subprocessors from training on customer data, and its model providers work under zero data retention. CoCounsel's FAQ says customer content and prompts do not train the product or the underlying models, and that partners including OpenAI and Google are contractually barred from training on customer data. From the AI Legal Index, based on each vendor's own published materials as of August 30, 2026. No vendor pays for placement.
Has either been tested by an outside evaluator?
Both took part in the February 2025 Vals Legal AI Report, run by an outside evaluator. Harvey also publishes BigLaw Bench, its own evaluation framework. From the AI Legal Index, based on each vendor's own published materials as of August 30, 2026. No vendor pays for placement.
What does Harvey cost compared with CoCounsel?
Neither lists a rate. CoCounsel sets out tier names and feature splits, with separate plans for law firms, corporations and government. Harvey sells through its sales team, with no pricing page and every commercial path running through a demo request. From the AI Legal Index, based on each vendor's own published materials as of August 30, 2026. No vendor pays for placement.
Neither vendor paid for inclusion, placement or a grade, and neither reviewed this page before it published. Everything on it comes from public material on the dates shown. How the index grades.
CoCounsel Legal belongs to Thomson Reuters, which also owns Westlaw and Practical Law, the content its answers draw on. Harvey is venture backed and names no parent company. Neither vendor reviewed this page.