Definition
A Latin citation signal meaning "in the same place." When used in legal writing, briefs, or footnotes, ibidem (abbreviated ibid. or ib.) directs the reader to the exact same source — and typically the same page or section — cited immediately before. It is not an independent legal concept but a citation mechanics term that appears throughout legal scholarship, court opinions, and historical treatises.
Common Language
Modern common usage (Wiktionary): "In the same place; indicates a reference to the same source as the previous one."
Historical common usage (Webster's 1913): "In the same place; abbreviated ibid. or ib."
The common and legal meanings are essentially identical here. The only distinction worth noting is register: in general writing, ibid. appears across academic disciplines; in legal writing, it carries the additional expectation that page-level precision matters, since courts and practitioners depend on pinpoint citations to verify authority. A researcher should not assume ibid. in a historical legal text means exactly the same page — it may mean the same volume, chapter, or case, depending on the author's convention.
Common Confusion
Ibidem is frequently confused with idem (meaning "the same author" or "the same person") and with op. cit. (opere citato, meaning "in the work cited," referring to a source cited earlier but not immediately before). The practical difference matters in legal research: ibid. tells you the source is the one immediately preceding; op. cit. tells you the source appeared somewhere earlier in the same document. Historical legal treatises use all three interchangeably at times, which can send researchers to the wrong volume or passage.
Why It Matters in Research
Ibidem is a navigational hazard in historical legal sources. In 18th- and 19th-century treatises — Blackstone's Commentaries, Kent's Commentaries, Story's works — ibid. was used with varying precision. Some authors used it to mean the same page; others, the same section; others, the same volume. When a historical treatise chains several ibid. references together, a single misread early in the chain corrupts every subsequent citation.
In Law Mind corpus research, this term surfaces most often in footnotes and marginal citations, not in the body text of opinions or statutes. When tracing a historical doctrine through secondary sources, researchers should not stop at an ibid. but should resolve it back to the root citation, particularly when the chain spans multiple pages or sections. Digitized versions of older treatises sometimes break footnote chains through scanning errors or page-image misalignment, making ibid. resolution especially unreliable without access to the physical source.
The abbreviation ib. (the shorter form) appears more commonly in very old texts and can be mistaken for other abbreviations in degraded print. Burrill's entry notably adds a broader gloss — "in the same thing, matter or case" — which reflects its occasional use in legal argument to mean "in the same proceeding" rather than strictly as a citation signal. Researchers working in pleading records or case narratives should watch for this extended sense.
Historical Dictionary Support
All three source dictionaries agree on the core Latin meaning: "in the same place." Black's (both editions) specifies the citation context — same book, same page — and confirms the standard abbreviations ibid. and ib. The second edition's entry appears to render the abbreviation as "ébid." which is a typeface or scanning artifact, not a variant form; the intended abbreviation is ibid.
Burrill's entry is the most legally textured of the three, adding "in the same thing, matter or case" alongside the standard meaning. This suggests Burrill recognized that the term functioned in legal writing beyond pure citation mechanics. None of the historical dictionaries address the confusion with idem or op. cit., and none flag the chain-citation problem. Webster's 1913 is, on this term, indistinguishable from the legal dictionaries — the common meaning and the legal meaning have always tracked together.
Encyclopedia Cross-Reference
See Law Mind Encyclopedia: Legal Citation Conventions; Latin Terms in Legal Writing.