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How Lexis+ AI Delivers Hallucination-Free Linked Legal Citations

April 30, 2024 (3 min read)
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By: Serena Wellen, Vice President of Product Management, LexisNexis 

We raised some eyebrows last fall when we announced the launch of Lexis+ AI, our new generative artificial intelligence (Gen AI) solution designed to transform legal work, “with linked hallucination-free legal citations” that are grounded in the world’s largest repository of accurate and exclusive legal content from LexisNexis. 

LexisNexis harnesses the power of Large Language Models (LLMs) to generate the highest quality answers with validated citation references. LLMs’ ability to reason and to minimize hallucination has become quite impressive with the proper techniques. One of these is known as Retrieval Augmented Generation (RAG).

RAG is a technique for enhancing the accuracy and reliability of Gen AI models with facts fetched from authoritative sources. The proprietary RAG platform we have built at LexisNexis enables Lexis+ AI to ground its responses directly in the most comprehensive collection of legal content, including case law (as reviewed by Shepard’s editors), statutes, Practical Guidance and more. 

This approach leverages our authoritative content to minimize hallucination risks found in off-the-shelf LLMs, check for the most up-to-date law and authority, and cite validated sources. It then ensures the answer contains verifiable facts and linked legal citations that are grounded in the closed universe of authoritative LexisNexis content. 

Every prompt in Lexis+ AI undergoes a minimum of five crucial checkpoints in our RAG platform to produce the highest quality answer: 

  • Lexical (word matches) and semantic (meaning and context) joint search retrieves the most relevant information by understanding the question you’re asking it to answer; 
  • Recency boost prioritizes results that are most current; 
  • Intelligent ranking leveraging authoritative data such as Shepard's™ Signal indicators elevates results that are most relevant and valuable for answering your question; 
  • Authoritative check pulls up high-value cases and courts to display the most authoritative results; and 
  • Citation validation ensures the cases it cites are real and delivers hallucination-free linked legal citations, confirming for you that the answer is grounded in truth. 

All of this happens in a matter of seconds. In fact, Lexis+ AI delivers answers 2X faster than Westlaw Precision AI and users in our commercial preview survey (November 2023) reported saving up to 11 hours per week using Lexis+ AI. 

In addition, it’s important to understand our promise is not perfection, but that all linked legal citations are hallucination-free. 

No Gen AI tool today can deliver 100% accuracy, regardless of who the provider is. Unlike other vendors, however, Lexis+ AI delivers 100% hallucination-free linked legal citations connected to source documents, grounding those responses in authoritative resources that can be relied upon with confidence. 

In the rare instance where a citation provided by Lexis+ AI does not include a link, users should always review the citation for accuracy. Remember, Lexis+ AI is meant to enhance the work of an attorney, not replace it. No technology application or software product can ever substitute for the judgment and reasoning of a lawyer. This is the same fundamental principle behind every tool in our tech stack. 

We are, in fact, pouring investment into our technology solutions and continuously refining safeguards that aim to deliver the highest quality answers. We are particularly committed to constantly improving the performance of our AI-powered solutions, including our breakthrough Lexis+ AI platform. 

Finally, it’s important to understand that we have placed humans in the loop at every stage in the creation of Lexis+ AI. 

Our Gen AI product development roadmap includes a commitment to create accountability through human oversight at every step in the process. We place individuals who are legal subject matter experts in the loop to continuously evaluate and track output quality, and we ask users to rate our Gen AI outputs and submit feedback. This ongoing customer engagement helps us refine and improve our solutions. 

These policies and processes are essential in ensuring the secure, responsible use of Gen AI. We take this role as our customers’ trusted partner very seriously. 

When we built Lexis+ AI, our goal was to deliver the most authoritative content from LexisNexis back to inform the answer. Our technical architecture, combined with the world’s largest repository of accurate and exclusive legal content, allows us to make that happen. That is how we are able to deliver on the promise of delivering to you 100% hallucination-free linked legal citations. 

To learn more or to request a free trial of Lexis+ AI, please go to