Definition of ignorantia juris non excusat
Ignorantia juris non excusat or ignorantia legis neminem excusat (Latin for "ignorance of the law does not excuse" or "ignorance of the law excuses no one") is a legal principle holding that a person who is unaware of a law may not escape liability for violating that law merely because he or she was unaware of its content. In the United States, exceptions to this general rule are found in cases such as Lambert v. California (knowledge of city ordinances) and Cheek v. United States (willfulness requirement in U.S. federal tax crimes).
European law countries with a tradition of Roman law use the expression nemo censetur ignorare legem: nobody is taught to ignore the law.
The rationale of the doctrine is that if ignorance were an excuse, a person charged with criminal offenses or a subject of a civil lawsuit would merely claim that he or she is unaware of the law in question to avoid liability, even though the person really does know what the law in question is. Thus, the law imputes knowledge of all laws to all persons within the jurisdiction no matter how transiently. Even though it would be impossible, even for someone with substantial legal training, to be aware of every law in operation in every aspect of a state's activities, this is the price paid to ensure that willful blindness cannot become the basis of exculpation. Thus, it is well settled that persons engaged in any undertakings outside what is common for a normal person, such as running a nuclear power plant, will make themselves aware of the laws necessary to engage in that undertaking. If they do not, they cannot complain if they incur liability.
The doctrine assumes that the law in question has been properly published and distributed, for example, by being printed in a government gazette, made available over the internet, or printed in volumes available for sale to the public at affordable prices.
In the criminal law, although ignorance may not clear a defendant of guilt, it can be a consideration in sentence, particularly where the law is unclear or the defendant sought advice from law enforcement or regulatory officials. For example, in one Canadian case, a person was charged with being in possession of gambling devices after they had been advised by customs officials that it was legal to import such devices into Canada. Although the defendant was convicted, the sentence was an absolute discharge.
In addition, there were, particularly in the days before satellite communication and cellular phones, persons who could genuinely be ignorant of the law due to distance or isolation. For example, in a case in British Columbia, a pair of hunters were acquitted of game offenses where the law was changed during the period they were in the wilderness hunting. In reaching this decision, the court refused to follow an early English law case in which a seaman on a clipper before the invention of radio was convicted even though the law had been changed while he was at sea (Bailey (1800) Russ & Ry 1).
This principle is also stated into law:
- Canada: Criminal Code (RSC 1985, c. C-46), section 19
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