Senior Machine Learning Engineer III

Are you passionate about building trustworthy Generative AI solutions that deliver accurate, source-grounded results?

Do you enjoy solving complex retrieval and search challenges while shaping the next generation of AI-powered legal and professional technology?

About our Team

LexisNexis Legal & Professional, which serves customers in more than 150 countries with 11,800 employees worldwide, is part of RELX (http://www.relx.com), a global provider of information-based analytics and decision tools for professional and business customers. Our company has been a long-time leader in deploying AI and advanced technologies to the legal market to improve productivity and transform the overall business and practice of law, deploying ethical and powerful generative AI solutions with a flexible, multi-model approach that prioritizes using the best model from today’s top model creators for each individual legal use case. The company employs over 2,000 technologists, data scientists, and experts to develop, test, and validate solutions in line with RELX Responsible AI Principles (https://stories.relx.com/responsible-ai-principles/index.html).

About the Role

We are seeking an AI Engineer focused on Retrieval-Augmented Generation (RAG) to help design, build, and optimize AI-powered experiences. In this role, you will contribute to the development of retrieval systems, evaluation frameworks, and source-grounded Generative AI solutions that enable users to access trustworthy and relevant information. You will work with advanced AI technologies while helping ensure quality, accuracy, and responsible AI practices.

Responsibilities

• Design, build, and optimize Retrieval-Augmented Generation (RAG) applications.
• Develop and manage document ingestion, chunking, embedding generation, retrieval, reranking, and source-grounded response workflows.
• Design and operate vector search solutions using modern vector database technologies.
• Validate retrieval quality, citation accuracy, relevance, coverage, and factual grounding using reproducible evaluation datasets.
• Collaborate with cross-functional teams to improve response quality and reduce hallucinations.
• Implement hybrid search strategies combining keyword, metadata, semantic/vector search, and reranking techniques.
• Monitor and evaluate retrieval performance, latency, cost, and AI system quality.
• Support the development of scalable and responsible Generative AI solutions across legal and professional information products.

Requirements

• Hands-on experience with Retrieval-Augmented Generation (RAG) applications, including document ingestion, chunking, embedding generation, retrieval, reranking, and source-grounded responses.
• Strong understanding of Generative AI and LLM capabilities, limitations, hallucination mitigation, and response-quality evaluation.
• Experience designing and operating vector search solutions using Qdrant, Pinecone, pgvector, LanceDB, OpenSearch vector search, or equivalent technologies.
• Ability to validate retrieval quality, citation accuracy, relevance, coverage, and factual grounding using reproducible evaluation datasets.

Preferred Qualifications

• Experience building AI agents or multi-step workflows with tool use, memory, and human review.
• Familiarity with agentic and LLM frameworks such as Google ADK, LangChain, LiteLLM, or MCP.
• Experience with hybrid search strategies combining keyword, metadata, semantic/vector search, and reranking.
• Experience applying RAG or Generative AI to legal, financial, publishing, or other highly regulated content domains.
• Knowledge of LLM observability, including monitoring latency, cost, retrieval performance, and unsafe or unsupported outputs.

Work in a Way That Works for You

We promote a healthy work/life balance across the organisation. We offer an appealing working prospect for our people. With numerous wellbeing initiatives, shared parental leave, study assistance and sabbaticals, we will help you meet your immediate responsibilities and your long-term goals.

Working Pattern

Working flexible hours - flexing the times when you work in the day to help you fit everything in and work when you are the most productive.

About the Business

LexisNexis Legal & Professional® provides legal, regulatory, and business information and analytics that help customers increase their productivity, improve decision-making, achieve better outcomes, and advance the rule of law around the world. As a digital pioneer, the company was the first to bring legal and business information online with its Lexis® and Nexis® services.