Boolean Search in Legal Research

Boolean search has been the foundation of computer-assisted legal research since the 1970s when Westlaw and Lexis first digitized case law. Lawyers construct queries using operators: AND requires both terms to appear, OR requires either term, NOT excludes documents containing a term, and proximity connectors (like /s for same sentence or /p for same paragraph) require terms to appear near each other. This approach gives researchers precise control over what they find.

Boolean search excels in several scenarios. When a lawyer needs to find every case that mentions a specific statutory section, Boolean search provides certainty. When a research trail must be reproducible for a peer or supervisor, Boolean queries produce identical results every time. When the research question involves precise terminology, such as a defined contractual term, Boolean search is more reliable than semantic search, which might return conceptually similar but textually different results.

However, Boolean search has well-known limitations. It requires lawyers to anticipate the exact language courts use, it returns documents rather than answers, and it can miss relevant authorities that use different terminology. The most effective modern approach combines Boolean search with semantic search, using each for its strengths: Boolean for precision and reproducibility, semantic for breadth and conceptual relevance.