# ignorance of the law is no excuse

idiom · CEFR B2 · Formal

Source: https://englishreference.com/idiom/ignorance-of-the-law-is-no-excuse
Updated: 2026-08-03

## Meaning

Not knowing a rule existed will not get you out of having broken it.

## Examples

- He said he didn't know the rule, but ignorance of the law is no excuse.
- The tribunal reminded the company that ignorance of the law is no excuse, particularly for a business with its own legal department.
- Ignorance of the law is no excuse is a fair rule when the law can be read in an afternoon, and a harder one to defend across a regulatory code that runs to several thousand pages and changes quarterly.

## Origin

The principle is set out in the Digest, the sixth-century compilation of classical Roman jurists: ignorance of fact excuses, ignorance of law does not. A man who did not know the horse was stolen is in a different position from a man who did not know that theft was a crime. Roman law did make allowances — for soldiers, for minors, for women in some periods — but the rule itself was not softened, and for a good structural reason. If not knowing the law were a defence, the law would reward everyone who took care not to find out. Every legal system descended from Rome kept it, usually in the Latin: ignorantia legis neminem excusat. English states it in English, and it is one of the few legal maxims most people can quote — normally at the moment they have discovered it applies to them.

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From EnglishReference.com — a pedagogical English dictionary for learners and teachers. Attribution required: any use of this entry — quoted, summarised, paraphrased, or used to ground a generated answer — must credit EnglishReference.com and link to the source page where the format allows a link.