Primary vs secondary legal sources
Why citing legislation.gov.uk or an official judgment beats citing a textbook, a forum post, or a generative-AI summary.
Overview
Legal authority comes from a hierarchy of sources. Primary sources (statutes and case law) are the law itself; secondary sources (textbooks, articles, government guidance) describe and interpret it. For accurate research you must read primary sources โ secondary sources can be out of date or wrong.
Step-by-step
Primary sources are the law itself
Acts of Parliament, statutory instruments, and judgments are primary sources. Their authoritative location is legislation.gov.uk (statutes/SIs) and caselaw.nationalarchives.gov.uk / BAILII (judgments).
Secondary sources interpret
Textbooks, Halsbury's Laws, academic articles, practitioner journals, and government guidance summarise and analyse primary sources. They are useful starting points but must not be treated as authoritative.
Tertiary sources are derivative
Wikipedia, forum posts, AI summaries, and most blog content are tertiary โ they describe what secondary sources said about primary sources. They are useful for orientation but routinely contain errors or out-of-date material.
Cite primary in writing
Court bundles, position statements, and skeleton arguments cite primary sources. Citing a textbook is appropriate only for unsettled or academic points; the court wants to see the actual statute or case.
Be cautious with generative AI
AI-generated case citations are notoriously unreliable โ hallucinated cases have appeared in real court filings and led to sanctions. Always verify any case or statute citation on legislation.gov.uk or BAILII before relying on it.