Legal AI for enterprises · For software consultancies
Gaius-Lex is a legal AI platform with a documented REST API. Your team integrates it with the client's documents and workflows. We supply legal retrieval, citation checks and a private deployment option.
Only for the reasons listed in Annex 2. The agreement runs for a fixed term, and clause 14.2 limits early termination to that list, read together with Annex 2, item 4.
The reason given in Supplier_letter_0926.pdf is not on the list. Two points need your decision.
The project you know
A General Counsel at one of your enterprise clients wants an assistant for contract review and legal research. Your team builds a prototype on a general model in two weeks. The demo goes well.
Then the client's lawyers try it on live matters. One answer cites a judgment that does not exist. The CISO asks where prompts are processed and who can be compelled to hand them over. Procurement asks who answers for the sources.
Answering those questions in-house means a legal database, retrieval tuned to legal text, a citation check and a private deployment path. That is months of work before the first invoice.
Gaius-Lex gives your team that layer as a platform. You keep the client relationship, the integration and the delivery.
Comparison
Microsoft 365 Copilot and ChatGPT Enterprise are capable general assistants. Your client will ask why the project needs anything else. The table answers on the points a legal deployment review checks, and each cell about another vendor links to that vendor's documentation or a public record.
| Review question | Microsoft 365 Copilot | ChatGPT Enterprise | Gaius-Lex Cloud | Gaius Vault |
|---|---|---|---|---|
| Where the model runs | Microsoft cloud. Since 17 April 2026 flex routing is on by default for EU tenants and allows inference outside the EU at peak demand. Admins can switch it off. | OpenAI cloud. Data at rest in Europe for new workspaces, in-region inference for eligible customers. | Gaius-Lex managed cloud | On a dedicated appliance in the client's office |
| Web search | Search queries go to Bing, outside the EU Data Boundary, and may contain parts of the prompt. | Web search available | No web search. Searches run only against the Gaius-Lex legal database, updated daily | No external calls |
| Provider jurisdiction | US company, in scope of the US CLOUD Act. Microsoft France told the French Senate under oath in June 2025 that it could not guarantee EU data would never reach US authorities. | US company, in scope of the US CLOUD Act. | EU company | The client's premises and jurisdiction |
| Legal sources | The client's Microsoft 365 content and the open web | Model knowledge, uploaded files and the open web | Case law, legislation, regulator decisions and the client's own documents | Same sources, stored on the appliance |
| Citation check | Links to web pages | Links to web pages | A separate verification pass checks case numbers and quoted passages | Same |
| Works without internet | No | No | No | Yes |
| Integration | Microsoft Graph, Copilot Studio | OpenAI API (a separate product) | REST API for search, answers, agent, OCR, anonymisation and verification | Same API, on the client's network |
Compiled in October 2026 from public vendor documentation. Vendors change defaults; check the current version before a client review.
What the research shows
Researchers from Stanford and Yale ran more than 200 legal research queries through three commercial legal research products and GPT-4. The products that retrieve from a legal database hallucinated far less often than the general model. None of them reached zero. Gaius-Lex runs verification as its own step, so you see which citations were confirmed before you rely on the answer.
Vals AI tested legal research products, ChatGPT and practising lawyers on 200 US legal research questions. ChatGPT scored as well as the specialised products on accuracy. On authoritativeness, which measures whether the answer rests on valid primary law, the legal products led by six points.
Any modern model will often reach the right answer. Your client's lawyers still sign under the sources. Gaius-Lex ranks primary law first, shows where each source sits in the hierarchy and flags provisions amended since the date that matters.
How it works
Think of a careful trainee. She searches the library first, writes second, and a senior colleague checks every footnote before the memo reaches you. Gaius-Lex follows the same order.
When a question lacks facts that change the answer, such as the type of contract or the relevant date, the platform asks before it searches.
Keyword search (BM25) finds exact strings like article numbers and case references. Vector search finds passages that say the same thing in other words. The two lists are merged and re-ranked.
A supreme court judgment ranks above a first-instance ruling. A provision in force on the relevant date ranks above one that has since been amended.
Every statement in the answer links to the passage that supports it.
A separate pass opens each cited document and checks that the case number exists and the quoted reasoning appears in it. Anything it cannot confirm is flagged.
You see the flag before you see the polish.
The platform
One platform for legal research, document work and automation — built in Europe, made for cross-border work. It runs where the data has to stay, opens inside the tools lawyers already use, and connects to the rest of the stack through one API.
EU-only cloud or an appliance in the office. Post-quantum encrypted. Never used to train models.
A provision, a judgment, a case number — checked before it reaches the lawyer.
Word, Outlook, Gmail, SharePoint, Drive and a phone. No new window to learn.
Every capability is also an API endpoint, ready to plug into existing systems.
1 · Where it runs
Gaius-Lex Cloud
All processing in the EU — not even the UK.
Files encrypted with keys held by users, post-quantum cryptography from day one.
Data is never used to train models.
New features and legal sources arrive without an upgrade project.
Fits: pilots, growing legal teams, organisations without their own GPU infrastructure.
A dedicated appliance with the AI models and legal sources preinstalled.
Plugs into the LAN with a single IP address.
Runs fully offline. Updates only through a relay the owner controls.
Hardware, licence and support under one contract.
Fits: banks, regulated in-house teams, any policy that bars external models.
Post-quantum cryptography
Documents stored in Gaius are protected with post-quantum cryptography from day one — against today's attacks and against “harvest now, decrypt later”, where stolen data waits for a quantum computer to break it.
Start in the cloud, move on-premise later: the same API, the same skills, the same integrations.
2 · What it does
Each capability is a screen in the Gaius app and an endpoint in the API — used as it is, or wired into the systems a team already runs.
Research
Documents
Automation
3 · Where it opens
Adoption is where most legal AI projects stall. Gaius opens in the tools lawyers already have on screen every morning.
Word Research and review beside the draft. 
Outlook Work on attachments without downloading them. 
Gmail Analyse what arrives, answer from the inbox. 
SharePoint Connect the libraries where matters live. 
OneDrive Personal files, same permissions. 
Google Drive Shared drives, searchable from Gaius. 
Gaius Meet Google Meet transcripts straight into the matter. 
Android Scan a document in court, ask about it on the way back. 
iOS The same workspace on iPhone and iPad. 4 · How it connects
IT teams and integrators connect Gaius to document systems, intranets and internal tools — without building the legal layer themselves.
Search, answers, the agent and document analysis behind one interface.
Separate access and a clear audit trail for every connected system.
Long analyses run as jobs and report back by webhook.
Hands-on workshops and skill onboarding with the team that built the product.
searchansweragentfilesdoc-verificationabusivitythesesregistriesocrPlanning legal AI for an organisation? Let's look at the architecture together.
API
Your developers connect Gaius-Lex to a document management system, a contract lifecycle tool or an internal portal. Long tasks run asynchronously and report back by webhook or polling.
/api/v1/searchFull-text search across legal sources, full documents by ID/api/v1/answerResearch answers with citations/api/v1/agentMulti-step legal agent that plans and calls tools/api/v1/doc-verification/pollChecks citations and case numbers in a document/api/v1/anonymizationRemoves personal data from text/api/v1/ocr/pollExtracts text from scanned files/api/v1/external/vectorizeIndexes the client's own documents/api/v1/query-documentsSearches those documents semantically/theses-analysis · /rule-analysis · /abusivitySpecialised analyses, in betaOrganisation API keys, with separate child keys per integration, so each client system can be revoked on its own.
# 1. Submit a question
curl -X POST https://api.gaius-lex.pl/api/v1/answer/poll \
-H "Authorization: Api-Key $GAIUS_API_KEY" \
-H "Content-Type: application/json" \
-d '{
"question": "Can the supplier terminate
a fixed-term agreement early?",
"simplify": false
}'
# 2. Fetch the result by the returned id
curl https://api.gaius-lex.pl/api/v1/answer/poll/<uuid> \
-H "Authorization: Api-Key $GAIUS_API_KEY"
# Webhook mode: POST /api/v1/answer with an endpoint
# for the callback instead of polling.Working together
You bring the client's use case. We join the technical discovery call when you want us there.
We supply the data-flow diagram and answer the client's vendor questionnaire, so your team does not have to research our side.
Your developers integrate the API with the client's systems. You get test keys and a named technical contact at Gaius-Lex.
We configure skills, reusable agent routines for work the client repeats, such as NDA review. Workshops for the client's lawyers run with your team or ours.
Your client gets legal AI that passes review. Your team keeps the delivery and the relationship.
Regulation
| Regulation | What the client's review asks | What we provide |
|---|---|---|
| GDPR | Where personal data is processed and by whom | Data processing agreement, subprocessor list, data-flow diagram |
| EU AI Act, Art. 50 | Transparency obligations, applicable since 2 August 2026 | Every output ends with a note that the content was generated with Gaius-Lex. We do not add watermarks to the text itself |
| DORA | Banks and insurers must manage ICT third-party risk, since 17 January 2025 | Answers to the ICT vendor due diligence, an exit plan, Vault as an on-premise option |
| NIS2 | Supply-chain security of essential and important entities | A description of our security measures |
Coverage depends on where your client operates. Tell us the countries and we confirm the available sources before the project starts.
A developer who works with REST APIs and webhooks.
No. Documents and prompts are used only to answer that client's queries. They are never used to train models.
Yes. Documents are encrypted and only their owner has access to them. On-premise deployment is also available.
Leave your phone number and email. A solution architect from Gaius-Lex replies with a proposed architecture and the next step.