Lead Applied Scientist, Search & Information Retrieval

Lead Applied Scientist, Search & Information Retrieval About the Role This role sits within the applied science function. You will own the design, development, and production deployment of large-scale search and information retrieval systems that power Westlaw, Practical Law, CoCounsel, and next-generation Thomson Reuters search experiences. The problems are real, the scale is large, and the expectation is shipped, reliable, measurable impact. You will work across retrieval architectures, indexing pipelines, ranking and re-ranking systems, semantic retrieval, hybrid search, and retrieval optimization for complex legal, tax, and accounting content. Multiple product teams depend on what this function delivers.  About You You hold a PhD in Computer Science, Information Retrieval, Machine Learning, NLP, or a related field, with 8+ years of post-degree industry experience building and deploying search and retrieval systems at scale. You have hands-on depth across indexing, retrieval, ranking, relevance evaluation, and production deployment. You publish, you mentor, and you measure success by what ships and performs in production. You understand search beyond simply consuming vector databases or retrieval APIs. You have built, optimized, and evaluated search systems that solve real user problems.  What You'll Do Design and deploy search architectures supporting large-scale legal, tax, and enterprise content collections Build and optimize ingestion pipelines that analyze, enrich, and prepare documents for retrieval Develop ranking and re-ranking systems using both traditional IR techniques and modern LLM-based approaches Improve retrieval quality through semantic retrieval, hybrid retrieval, query understanding, and relevance optimization Design evaluation frameworks for retrieval performance, relevance, ranking quality, and end-user outcomes Lead technical decisions around indexing strategies, retrieval architectures, ranking models, and search infrastructure Partner with engineering teams to deliver scalable, reliable, and performant search services Contribute to the development of self-service search platform capabilities used by internal product teams Provide technical input to senior leadership on search, retrieval, and AI strategy Mentor applied scientists and machine learning practitioners across the organization Required Qualifications PhD in Computer Science, Information Retrieval, AI, Machine Learning, NLP, or a related field preferred 8+ years of industry experience building production search, information retrieval, ranking, or recommendation systems Publications at SIGIR, ACL, EMNLP, NeurIPS, ICLR, KDD, WWW, or equivalent venues Strong production Python skills and experience with PyTorch, Hugging Face Transformers, and distributed model development Hands-on production depth required in: Search engine architecture, indexing systems, and ingestion pipelines Ranking and re-ranking systems rather than solely consuming search technologies Information retrieval, semantic retrieval, hybrid retrieval, and vector search architectures Query understanding, relevance optimization, and search evaluation methodologies Retrieval systems supporting large collections of text-rich content LLM-enhanced retrieval, RAG architectures, and retrieval optimization End-to-end measurement and evaluation of search quality and user outcomes Preferred Qualifications Experience with legal, regulatory, tax, scientific, or other text-heavy domains Building retrieval systems over large enterprise knowledge repositories Experience with Elasticsearch, OpenSearch, Solr, Vespa, or similar search technologies API platform development and self-service search platforms Agentic AI systems that incorporate retrieval capabilities AzureML or AWS SageMaker Experience building systems that combine search, retrieval, and document understanding capabilities #LI-SM2 This posting is for proactive recruitment purposes and may be used to fill current openings or future vacancies within our organization. What’s in it For You? Flexibility & Work-Life Balance: Flex My Way is a set of supportive workplace policies designed to help manage personal and professional responsibilities, whether caring for family, giving back to the community, or finding time to refresh and reset. This builds upon our flexible work arrangements, including work from anywhere for up to 8 weeks per year, empowering employees to achieve a better work-life balance. Career Development and Growth: By fostering a culture of continuous learning and skill development, we prepare our talent to tackle tomorrow’s challenges and deliver real-world solutions. Our Grow My Way programming and skills-first approach ensures you have the tools and knowledge to grow, lead, and thrive in an AI-enabled future. Industry Competitive Benefits: We offer comprehensive benefit plans to include flexible vacation, two company-wide Mental Health Days off, access to the Headspace app, retirement savings, tuition reimbursement, employee incentive programs, and resources for mental, physical, and financial wellbeing. Culture: Globally recognized, award-winning reputation for inclusion and belonging, flexibility, work-life balance, and more. We live by our values: Obsess over our Customers, Compete to Win, Challenge (Y)our Thinking, Act Fast / Learn Fast, and Stronger Together. Social Impact: Make an impact in your community with our Social Impact Institute. We offer employees two paid volunteer days off annually and opportunities to get involved with pro-bono consulting projects and Environmental, Social, and Governance (ESG) initiatives. Making a Real-World Impact:   We are one of the few companies globally that helps its customers pursue justice, truth, and transparency. Together, with the professionals and institutions we serve, we help uphold the rule of law, turn the wheels of commerce, catch bad actors, r