Microsoft Copilot vs CoCounsel vs Harvey: add-on, Westlaw AI or platform

Copilot vs CoCounsel vs Harvey at a glance

The choice turns on what your Microsoft license already includes, whose legal content the answers rest on, and how much platform your firm wants to roll out. Gavel Exec is in the last column.

Three kinds of purchase: a license feature, a content bundle, a platform

Copilot for Legal is a feature of a license many organizations already hold. Microsoft's support documentation describes it as legal capabilities for Copilot in Word desktop and Cowork, and its October 15, 2026 announcement counts more than 20 legal skills plus partner-built plugins. Microsoft's message center notice MC1509799 says the Word plugin is enabled by default for users with Microsoft 365 Copilot commercial licenses and that Cowork users add the legal plugin themselves.

CoCounsel Legal is a content bundle with an assistant on top. Thomson Reuters sells CoCounsel Essentials, Westlaw Advantage and the Practical Law Dynamic Tool Set as one subscription, and its product page lists add-ins for Word, Outlook and Teams. The buyer pays for the research library as much as for the AI.

Harvey is a platform a firm deploys. Its homepage lists Agents, Vault, Knowledge, Spaces and Contract Intelligence among its products, counts 3,500+ law firms and in-house legal teams and 80+ Am Law 100 firms as users, and sends every visitor to "Request a Demo."

Harvey announced on June 16, 2026 that it is available as an agent inside Microsoft 365 Copilot and as a plugin inside Copilot Cowork. Microsoft's launch list of partner plugins includes HighQ from Thomson Reuters, and LawNext reported that Westlaw, CoCounsel and LexisNexis were absent from it.

Where the law comes from: partner plugins, Westlaw or Ask LexisNexis

CoCounsel is the only one of the three whose listed price includes a licensed case-law library. Its answers draw on Westlaw and Practical Law as well as the firm's own documents, and the product page cites Practical Law Global guidance spanning over 100 jurisdictions.

Harvey's research product is Knowledge, and its United States primary law comes through Ask LexisNexis. Harvey's help center says the feature returns case law from federal and state courts along with statutes and regulations, flags through Shepard's whether a decision remains good law, and is "a paid add-on feature within Harvey" that needs no existing LexisNexis subscription.

Copilot for Legal ships without a research database. Microsoft's transparency documentation warns that Copilot "is not jurisdiction-aware by default" and that its output "may not incorporate live legal databases." Research arrives through partner plugins that began rolling out on October 15, among them Bloomberg Law and Trellis, and each depends on what the firm licenses from that partner.

Playbook review in Word: three rule formats

All three check a contract against a playbook inside Word and return tracked changes. The differences lie in rule authorship and in the labels each tool puts on a finding.

Copilot for Legal. Microsoft's getting started page says the playbook must be a .docx file. Copilot sorts it into topics, each topic carries rules and sample clauses you may revise before the review starts, and you accept or dismiss each proposed tracked change. Review works only from playbooks today, Copilot can also draft a playbook when given several precedents, and Microsoft cautions that it may miss relevant clauses in complex or lengthy documents.

CoCounsel for Microsoft Word. The "Compare to playbooks" feature lets you pick between playbooks you built and ones Practical Law pre-built. According to the Thomson Reuters help center, each clause comes back flagged as missing, having issues or acceptable, and findings are grouped as high risk issues, major issues and minor issues.

Harvey for Word. A Harvey playbook holds a standard position and fallback positions for each rule. Harvey's playbooks guide says each clause is labeled Acceptable, Needs review or Not acceptable, the edit you pick lands as a redline with an optional justification comment, and designated Playbook managers maintain the rules.

CoCounsel suits a team that wants to begin from Practical Law's positions, and Harvey suits a firm that wants central control over who edits the rules. Copilot is the fastest start when the playbook already lives in a Word document.

Word versions, Mac support and rollout dates

Availability differs by desktop and country, so check it before comparing features. Microsoft's legal pages name Word desktop and Cowork and mention no other Word version, its testing was primarily in United States English, and the message center notice expects the general availability rollout to finish by mid-December 2026.

For Harvey for Word, Harvey's help center says a Windows computer is recommended and suggests that anyone on a Mac try Word Online. Thomson Reuters' September 2026 release notes limit the next-generation CoCounsel Legal agent in Word to the United States. Ask each vendor to confirm coverage for Mac users and offices abroad.

Bulk review and document systems

Harvey and CoCounsel publish capacity numbers, and Microsoft describes tasks. A Harvey vault holds up to 100,000 documents, and a review table extracts the same data points from thousands of those files at once. CoCounsel's published limit is 100 questions asked of up to 10,000 documents. Microsoft says Cowork can compare key terms across agreements, with no document limit stated.

For document management systems, CoCounsel's product page lists iManage, NetDocuments and SharePoint. Harvey's Vault page names iManage, SharePoint and Google Drive for syncing. Copilot works with content a user can already open in Microsoft 365, including approved precedents in SharePoint, and Microsoft's partner list adds plugins from iManage Work, NetDocuments and Box.

Pricing, terms and who can buy today

Copilot has the lowest listed price of the three and Harvey lists none. CoCounsel sits between them with a starting price for small firms. Microsoft's $30.00 is the price of an add-on that requires a separate license for a qualifying Microsoft 365 plan. For a like-for-like comparison, Gavel Exec's $160 per user per month includes built-in legal playbooks, benchmarking and 1,000 queries per user per month.

• Microsoft. The Microsoft 365 Copilot add-on costs $30.00 per user per month when paid yearly and $31.50 when paid monthly under an annual commitment, and it requires a separate qualifying Microsoft 365 plan. Microsoft's business pricing page shows the Microsoft 365 Copilot Business add-on at $18.00 yearly (a first-year promotional price offered until December 31, 2026, against a regular $21.00) and $25.20 on a monthly subscription. That page puts Copilot Cowork under usage-based billing, so ask how legal work in Cowork is charged.
• Thomson Reuters. On the small-firm page, the CoCounsel Legal card reads "Starting at" $551.85/month, with no word on whether the figure covers one attorney or the whole firm. The plans page offers 1-year, 2-year and 3-year plans and says online pricing is for new customers only. Thomson Reuters tells firms with more than 10 attorneys to contact sales.
• Harvey. No price, seat minimum or contract length appears on harvey.ai, and Ask LexisNexis costs extra. Harvey's mid-sized firm page is written for firms of roughly 15 to 150 lawyers and says a Customer Success Manager and Legal Engineers are assigned to the rollout.

Microsoft's business plans offer a free month that needs a credit card and converts to paid unless you cancel, and Microsoft says no trial is available for the $30.00 add-on. Thomson Reuters offers a CoCounsel free trial by request, and Harvey starts with a demo.

Security, data use and model choice

Each vendor says customer content is not used to train the underlying models, and each documents its controls differently. Microsoft says Copilot works only with content each user can access, honors sensitivity labels and processes data within the Microsoft 365 service boundary, so documents already stored there go to no new vendor.

Thomson Reuters' product page reads "SOC 2 and ISO 42001 certified"; the type of SOC 2 report goes unstated, so ask for it. Harvey's security page describes yearly SOC 2 Type II audits plus ISO 27001, Zero Data Retention required of model providers and hosting in Microsoft Azure with regional storage options. Harvey also documents a choice of model: its help center lists OpenAI, Anthropic and Google models, picked automatically unless a workspace administrator enables the Model Selector.

Which should you choose?

• Choose Microsoft Copilot for Legal if your organization already pays for Microsoft 365 Copilot, your lawyers work in Word desktop in United States English, your playbook is a Word document, and legal research comes from a separate subscription.
• Choose CoCounsel Legal if answers must rest on Westlaw and Practical Law, you want Practical Law pre-built playbooks and review of up to 10,000 documents, and a 1- to 3-year term is acceptable.
• Choose Harvey if one platform should cover research, drafting, playbooks and vaults holding up to 100,000 documents, rollout support matters to you, and a purchase that follows a demo and a quote is acceptable.
• Consider Gavel Exec if contracts are the bulk of what you would hand to Copilot, CoCounsel or Harvey (review, redlines and drafting in Word) and you want a published price you can test before paying: $160 per user per month, with the first 25 queries per user free.

A fourth option: Gavel Exec for the contract work

Many lawyers comparing these three mainly want the agreement on screen marked up against their own positions. Next to a general assistant and two broad legal platforms, Gavel Exec is the contract-specific choice: AI contract review and drafting software built for the solo, small and mid-sized firms, in-house legal teams and transactional attorneys who draft and negotiate in Word. It installs from Microsoft AppSource as a Word add-in for Windows, Mac, Word on the web and Microsoft 365, with a web app at exec.gavel.io.

• The redline: the entire agreement comes back as tracked changes ranked by priority, each one carrying Gavel Exec's reasoning, together with margin comments and a list of the terms that are missing.
• Playbooks: where Copilot needs the playbook as a .docx file, Gavel Exec generates playbook rules from a checklist, a spreadsheet playbook or agreements you have signed (.docx, PDF or .csv), and you can also begin with built-in playbooks that were developed with attorneys in corporate and real estate law.
• Benchmarking: the web app marks every provision on-market, off-market or missing, and you can filter by jurisdiction, industry and company size.
• Price and trial: paid plans cost $160 per user per month, or $1,740 per user per year, and give each user 1,000 queries a month. Billing is month to month with no long-term contract, and the trial is 25 free queries per user with no credit card and no sales call.
• Security: Gavel holds Zero Data Retention agreements with the AI model providers it uses, OpenAI among them, is SOC 2 Type II certified, and does not use customer data to train AI models. Hosting defaults to Amazon Web Services in the United States, with European Union, Canada and Australia regions offered.
• Results and builders: Martin Algie of MIA Contract Lawyers cut first-cut review from about 15 hours per contract to about 5 hours. Gavel is used by over 2,000 legal organizations in 28 countries, and its CEO and Founder, Dorna Moini, practiced as a litigation associate at Sidley Austin before she started the company.

Gavel Exec runs beside a research tool and checks sources against your precedent, uploaded matter files, EDGAR filings and government sources, because it is built for transactional work: litigation and e-discovery are covered by Relativity, Gavel's parent company, and there is no case-law research database or native iManage or NetDocuments connection today. The one-on-one pages are Harvey vs Gavel Exec, CoCounsel vs Gavel Exec and Microsoft Copilot vs Gavel Exec.

How to test Copilot, CoCounsel and Harvey side by side

1. Line up access. Ask your Microsoft 365 administrator whether the legal plugin has reached your tenant, request the CoCounsel Legal free trial and the Harvey demo the same day, and start Gavel Exec's 25 free queries.
2. Prepare one playbook as a Word file. Write your positions for one agreement type, with a preferred clause and a fallback for each point. Upload the .docx to Copilot, create a custom one in CoCounsel's Word add-in, ask Harvey to load it during the demo, and let Gavel Exec generate rules from the same file.
3. Run a contract you have already negotiated. Lay each tool's redline next to the markup that went to the other side, then check missing-clause handling and whether Copilot holds up across a long agreement.
4. Get the commercial terms in writing. From Microsoft: which plan includes the legal skills and how Cowork usage is billed. From Thomson Reuters: what the $551.85 starting figure covers (an attorney or the firm) and the renewal terms. From Harvey: the per-user price, seat minimum, term and the Ask LexisNexis fee.

More comparisons: CoCounsel alternatives, Harvey alternatives, Spellbook vs CoCounsel, Spellbook vs Harvey, every Gavel comparison and our list of Microsoft Word add-ins for lawyers.