Security: mostly the same pipes
Most legal AI platforms don't build their own AI. They rent it from the same three companies you'd buy from directly. Thomson Reuters names OpenAI and Google, and rebuilt its newest CoCounsel on Anthropic's Claude. Lexis lets you choose between Claude and GPT models. vLex says Vincent uses all three.
They reach those models under business terms: no training on your data, and a contract with you about how they handle it. That's the same protection ChatGPT Business and Claude Team give you. Next to a $20 personal plan, a legal platform is far safer. Next to a business plan, the gap is small.
Some do go a step further, and it's worth knowing which:
- Thomson Reuters says in its CoCounsel security FAQ that OpenAI and Google don't store CoCounsel prompts, and it turns off their abuse monitoring, so nobody at those companies reads your chats.
- LexisNexis runs its models privately inside Amazon's and Microsoft's clouds and deletes conversations after 90 days.
- vLex has zero-retention contracts with its AI providers and encrypts each customer's data with its own keys.
Compare Claude Team, where Anthropic keeps chats its safety systems flag for up to 2 years. So the legal platforms are a little stronger. They're not a different category.
Citations: the real difference
This is what the extra money buys. When you ask CoCounsel a research question, it searches Westlaw and links you to real cases. Protégé searches Lexis and runs Shepard's on the citations it gives you. Vincent searches vLex and flags bad law with CERT. ChatGPT can't do any of that. It can only search the open web, and it can invent a case that sounds right.
Grounded isn't the same as right. In 2024, Stanford researchers ran 202 legal questions through the legal tools. Lexis+ AI gave a wrong or unsupported answer about 17% of the time. Westlaw's AI-Assisted Research did it about 33% of the time. Thomson Reuters disputed the study and said its own testing showed about 90% accuracy. Both tools have changed since, and nobody independent has tested Westlaw's or Lexis's current versions. A 2025 benchmark of research tools scored the ones it tested, ChatGPT included, at 74% to 78%. Lawyers answering the same questions scored 69%. Westlaw and Lexis weren't in it.
Courts are not grading on a curve. A database of court decisions dealing with AI-invented citations had logged 1,514 US cases as of October 28, 2026. Massachusetts has its share:
- Smith v. Farwell (Norfolk Superior Court, 2024): $2,000 for four cases that didn't exist. The lawyer was later publicly reprimanded.
- Dastou v. Holmes (Middlesex Superior Court, 2025): the lawyer couldn't bill for the work and had to take a CLE course.
- Aguilar v. The Crawford Group (federal court in Boston, September 2026): sanctions, and permission to appear in the case revoked. The lawyer told the court he thought an enterprise-grade AI tool wouldn't hallucinate.
That last one is the trap. Paying more for the tool doesn't move the duty. You still open every case and read the line you're citing.
Are they more robust?
For legal research and drafting from law, yes. They know what a jurisdiction filter is, they draft in the forms lawyers use, and they're built around a library. CoCounsel and Protégé also do document review, timelines and deposition outlines.
For work on your own files, not really. Summarizing a grand jury transcript or finding where two statements conflict is reading, and ChatGPT and Claude read as well as anything built on top of them. Often they are the thing built on top of.
Each product, in more detail
CoCounsel Legal (Thomson Reuters)
The natural pick if you already use Westlaw. Its Deep Research mode returns linked Westlaw cases with the passages that support each point. Thomson Reuters says it doesn't train on your prompts or documents, and holds SOC 2 and ISO 42001 certifications for CoCounsel. Its small-firm pages list Westlaw Advantage with CoCounsel at $415.35 a month and CoCounsel Legal at $551.85. Ask about contract length before you sign. Third parties report 3-year terms.
Lexis+ with Protégé (LexisNexis)
The Lexis answer to CoCounsel. You can pick which AI model answers, and a Shepard's agent checks and links the citations in its answers. LexisNexis says not every answer in its general AI mode is grounded in Lexis content, so watch which mode you're in. No US price is published. LexisNexis advertises 15% off for new subscribers through bar member benefits.
Vincent (vLex, now Clio)
Clio bought vLex for $1 billion, announced in June 2025 and closed that November. Vincent searches vLex's library, links to the sources, and flags negative treatment with vLex's citator, CERT. Clio Work is Clio's AI workspace, sold to solos on its own since April 2026, and it now includes Docket Alarm's billion-plus court filings. Clio Manage also has its own built-in AI, once called Clio Duo and now Manage AI. It works on your matters inside Clio. It isn't a research library. None of the three has a current published price.
NexLaw
Founded in 2024 and based in Sydney. It does research and drafting (NeXa), evidence timelines (ChronoVault) and trial prep, and has a criminal defense page. It's the cheapest legal platform here with a published price: $2,999 a year for Essential, $3,999 for Professional, which adds timelines and a data processing agreement.
What to know if you're paying for it:
- It doesn't say which AI company it uses, which legal database it searches, or whether it has a citator. It says it links every citation to a source and audited a "99.9% citation match rate." Ask what was matched to what.
- Its pricing page promises "zero model training on client data." Its security page says user data isn't used "for purposes other than improving platform performance." Ask them to square those two.
- The data processing agreement comes with Professional, not Essential.
- Annual plans auto-renew and aren't refunded. Paying an annual plan monthly and cancelling early means paying out the rest of the year.
Paxton
A newer research and drafting tool with its own case database and citator, and a published price: $499 a month or $2,999 a year, with a 7-day trial. It says it's SOC 2 and ISO 27001 certified. It doesn't name the AI underneath or say whether it trains on your data.
For criminal defense specifically: JusticeText
Not a research tool. It transcribes body-cam and interview video, makes the transcript searchable with timestamps, and builds clips and timelines. Public defender offices use it. There's no price list. A 2021 county contract shows $100 per user per month. If your discovery is mostly video, this saves more hours than any research platform.
What you may already have in Massachusetts
- Massachusetts Bar Association members get Decisis free, a research tool from LexisNexis. It replaced Fastcase in December 2023. It's basic research, not Protégé.
- Social Law Library and Hampden County Bar Association are vLex bar partners. vLex offers bar partners' members basic research free and Vincent at a discount, not free.
- CPCS gives Westlaw to its own staff attorneys. Private bar advocates don't get it. CPCS points them to MyGideon and Social Law Library.
Check with your bar association before you pay full price for anything.
What I'd do
- Keep one business plan for your own documents: ChatGPT Business or Claude Team. Drop the $20 personal plan. Why.
- If you write motions every week, add one legal platform. Pick the library you already know: Westlaw means CoCounsel, Lexis means Protégé, and vLex or Social Law means Vincent.
- If you write a motion a month, you may not need one. Use your free bar research tool, and check what ChatGPT or Claude gives you against it.
- Whichever you use, run every citation through KeyCite, Shepard's or CERT, open the case, and read the page you're citing.
Four questions for any vendor
- Which AI company processes my data, and is it under that company's business terms with training off and zero retention?
- What agreement do you sign with me about my data, and does it come with my plan?
- Which legal database does it search, and does it run a citator on its own answers?
- What does it do when it can't find support for an answer: say so, or answer anyway?
A vendor that can't answer the third and fourth in plain English is selling you ChatGPT with a legal skin.
This guide covers what these companies publish, not legal advice. Prices and products change fast. The pages linked below are the current word.