Lexis+ AI

What is Lexis+ AI?

Lexis+ AI is the conversational generative artificial intelligence platform developed by LexisNexis (global leader in legal data founded in 1970). Officially launched in late 2023, the tool integrates large language models with the world's largest library of doctrines, case laws, regulations, and legal precedents, allowing lawyers and judges to research complex concepts and draft briefs with the confidence of obtaining responses backed by verified and official legal data sources.

How it works

Unlike conventional generative AIs (which can invent laws and fictional legal cases due to hallucinations), Lexis+ AI uses Retrieval-Augmented Generation (RAG) architecture. When the user asks a question (such as "What are the precedents on the civil liability of internet providers in the state of California?"), the AI does not answer off the top of its head. It conducts a real-time semantic search within LexisNexis' private collection, locates real decisions and articles, and uses the LLM to summarize the facts, responding to the user in explanatory text containing direct links to each of the original source decisions.

Key features

• Advanced Conversational Search: Ask legal questions in plain language and receive detailed and substantiated answers with links to real case law.
• Legal Document Drafting: Quick generation of initial drafts of briefs, judicial agreements, formal letters, and contract clauses.
• Automated Case Summarization: Condenses court decisions and long briefs of hundreds of pages into quick-read summaries with main arguments.
• Document Upload and Analysis: Allows uploading adversary briefs so the AI can analyze weak points of argumentation and suggest counter-arguments based on local laws.
• Data Security and Confidentiality: Private infrastructure that ensures that lawyers' case data and searches are never exposed or used to train public AI models.

Available integrations

As a feature integrated into the LexisNexis data suite, the AI tools work attached to Lexis+ search systems, allowing users to save searches directly to folders and share history with other team members.

Who it is for

• Lawyers and public defenders who need to optimize the speed of complex precedent searches.
• Judges and judicial clerks to quickly triage arguments and case law of active lawsuits.
• In-house legal departments of corporations to analyze briefs and assess active litigation risks.

Real-world use cases

1. Legal Thesis Development: A criminal defense lawyer uses Lexis+ AI to search all recent appeal decisions on a new digital evidence law, obtaining an ordered summary of successful and unsuccessful cases in less than 10 minutes.
2. Review of an Initial Brief: A tax lawyer uploads a collection brief sent by the public treasury. Lexis+ AI analyzes the foundations of the opposing brief and suggests three case law precedents from the same court that can be used to annul the collection.

Pricing

Pros and Cons

Pros:

• Almost completely eliminates the risk of legal hallucinations by anchoring answers to a verified real database.
• Every answer generated by the AI contains clear footnotes and links to primary sources of law.
• Excellent speed in reading and interpreting long legal documents.

Cons:

• Very high cost, marketed predominantly to large firms and large-scale government agencies.
• The deepest integrated case law and doctrine data is focused on the US and European jurisdictions.

Alternatives to Lexis+ AI

The main global competitors in legal research and AI platforms are:

• CoCounsel (by Thomson Reuters): The main direct competitor integrated into the Westlaw legal database.
• Harvey Legal AI: Focused on large firms with advanced due diligence support funded by OpenAI.
• Everlaw AI: Excellent platform focused on e-discovery and evidence analysis for complex litigation.