Casetext was the scrappy independent legal AI startup — until Thomson Reuters bought it for $650M in August 2023 and folded it into CoCounsel. Today, CoCounsel sits inside the Westlaw stack, starting at $500+/month per seat. Ark costs $29/month and isn't owned by anyone's legal publisher. Here's the head-to-head.
In June 2023, Thomson Reuters announced it would acquire Casetext for $650 million. The deal closed in August 2023. Within months, Casetext's flagship product — CoCounsel — was rebranded as a Thomson Reuters product and integrated into the Westlaw ecosystem.
For existing Casetext users, this was bittersweet. The independent legal AI they'd championed was now owned by the world's largest legal publisher. Pricing shifted upward. Feature roadmaps got absorbed into Westlaw's corporate agenda. The scrappy startup became an enterprise product.
Ark exists as a deliberate response to that consolidation. We're independent. We don't sell Westlaw subscriptions. We don't upsell Lexis add-ons. We build legal AI that works for attorneys and the public — priced to be accessible.
CoCounsel's pricing is largely bundled with Westlaw. Entry-level packages start around $500/month per seat for small firms; larger firms pay $1,000+/seat. There's no public $29 self-serve tier for CoCounsel.
Ark is $29/month. Flat. Month-to-month. No annual contract lock-in. No per-seat escalations. No "request a demo" sales gate.
| Feature | Ark | Casetext / CoCounsel |
|---|---|---|
| Monthly price | $29 | $500+ (bundled with Westlaw) |
| Self-serve signup | Yes | No — sales demo required |
| Ownership | Independent | Thomson Reuters |
| Case database | 7.4M opinions | Access via Westlaw |
| Court rules | 142K+ rules, 50 states | Varies by Westlaw tier |
| AI legal drafting | Yes (Opus-powered) | Yes (GPT-4 based) |
| Free trial | Yes, no credit card | Sales-gated demo only |
| Jurisdiction-aware search | Yes, per-state indexes | Limited |
Try independent legal AI for $29/month — no sales call required. Start searching 7.4M cases, 26.6M salient points, and 142K court rules today.
Start Free TrialLegal AI isn't just a product — it's an information pipeline. The company that owns your legal AI also owns the databases it pulls from, the annotations it cites, and the subscription model you pay into. When one company owns all three, conflicts of interest follow.
Casetext pre-acquisition: Built a reputation for independent, AI-native legal research. CoCounsel was a breakthrough — the first lawyer-facing LLM product. Attorneys loved it because it wasn't tied to Westlaw or Lexis.
Casetext / CoCounsel today: Deeply integrated into Westlaw. Pricing aligned with Thomson Reuters' enterprise contracts. The independence value prop is gone.
Ark's position: We are not owned by Thomson Reuters, LexisNexis, or Wolters Kluwer. We pull from public case law, public statutes, and public court rules — with Voyage-powered semantic search and Isaacus Kanon-2 legal reranking. No proprietary database paywall. No upsell to enterprise products you don't need.
Both Ark and CoCounsel use modern LLMs for legal drafting, summarization, and research. The difference is in how citations are grounded.
CoCounsel approach: Draws on Westlaw's proprietary content — headnotes, KeyCite, annotations. Citations can link into paywalled content, which is powerful for Westlaw subscribers but adds vendor lock-in.
Ark approach: Citations are grounded in Ark's searchable database of 7.4M case opinions and 26.6M salient points. Every cited case is clickable and verifiable. The AI cannot hallucinate cases because every citation must resolve to a real record in the index.
For solo attorneys and small firms doing typical case research, both tools produce usable work product. Ark's edge is cost and portability — your citations aren't locked into a Westlaw subscription.
Ark's database is partitioned by jurisdiction. When you set your active state to, say, Florida, searches return Florida statutes, Florida court rules, Florida appellate opinions — not noise from California or New York. This dramatically improves relevance for practicing attorneys.
CoCounsel inherits Westlaw's jurisdiction structure, which is comprehensive but less tuned for solo per-state workflows. If you practice multi-state and need deep historical research across 50 jurisdictions, Westlaw's backend gives CoCounsel an edge. If you practice in one or two states, Ark's per-state indexes are faster and cleaner.
Not really. Since the Thomson Reuters acquisition, Casetext has been progressively folded into CoCounsel and the Westlaw product family. Standalone Casetext subscriptions have been phased out in favor of the CoCounsel branding inside Westlaw.
CoCounsel pricing is not published publicly. Reported entry points start around $500/month per seat, bundled with a Westlaw subscription. Annual contracts are standard. For comparison, Ark is $29/month, self-serve, with no annual commitment.
Ark handles the core CoCounsel workflows: AI-powered legal research, case summarization, document analysis, brief drafting assistance, and citation verification. What Ark doesn't do: pull from Westlaw's proprietary annotations (KeyCite, headnotes). For most solo and small-firm work, Ark's database is sufficient. If you need Westlaw's proprietary content specifically, CoCounsel is the better fit.
If your firm already has a Westlaw enterprise subscription, CoCounsel integrates naturally. Large firms with $1M+ annual research budgets may find the integration worth the premium. For solos, small firms, and independent practitioners, Ark's $29/month gives 80%+ of the utility at 5%+ of the cost.
No. Ark's AI is grounded in a retrieval pipeline — every citation must resolve to a real record in the 7.4M-opinion database. Hallucinated case names cannot appear because there's nothing in the index to retrieve. This is the same safeguard that makes modern CoCounsel reliable, but Ark implements it on an independent, Voyage + Isaacus Kanon-2 stack.
Choose Ark if:
Choose CoCounsel if:
Bottom line: Casetext was once the independent alternative. Since the Thomson Reuters acquisition, that role is vacant. Ark fills it — at a fraction of the cost, with the same AI grounding principles, and without the enterprise sales gate.
Ready for independent legal AI? Ark is $29/month, month-to-month, and ships with the full jurisdiction-aware research stack CoCounsel users expect.
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