Duhaime's Law Dictionary

Ignorantia Juris Non Excusat Definition:

Latin: ignorance of the law is no excuse.

Related Terms: Mistake, Ignorance of the Law

Also, alternatively:

  • ignorantia juris haud excusat; and
  • ignorantia juris neminem excusat.


The original Latin form of ignorance of the law is no excuse, but more properly stated, in law, ignorance of the law is no defence as the maxim is firmly grounded in criminal law and firmly excluded from the realm of civil disputes.

In Mens Rea in Statutory Offences, the author wrote:

"At least one thing is crystal clear, namely, that it does not involve proof that the accused knew that he was committing a criminal offence. It has always been accepted as an axiomatic principle that ignorance of the law is no excuse....

"It has always been accepted as an axiomatic principle that ignorance of the law is no excuse. Were the position otherwise it is obvious that the legislature's handiwork could be flouted indiscriminately, an offender taking care to insure that he did not make himself cognizant with the law."

In regards to the exclusion of the maxim in civil law disputes, from Lansdown:

"That maxim of law, ignorantia juris non excusat, was in regard to the public, that ignorance cannot be pleaded in excuse of crimes, but did not hold in civil cases"

In Nepean, Justice Dickson of Canada's Supreme Court wrote:

"The maxim ignorantia juris non excusat has no relevance to the case of a man seeking to recover back money paid by him in misapprehension of his legal rights...."

Or in Rollinson, Justice Muldoon:

"The rule of criminal law, ignorantia juris non excusat ... applies only to criminal law."

Often distinguished from ignorantia facti excusat. Ignorantia facti excusat, ignorantia juris non excusat: ignorance of fact excuses; ignorance of law does not excuse.



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