The Grammarphobia Blog

How illegal is unlawful?

Q: In British law there seems to be a difference between “illegal” and “unlawful.” Is there the same distinction in the US, and if so, what is the difference for you?

A: Bryan A. Garner, a lexicographer, lawyer, and teacher, writes in A Dictionary of Modern Legal Usage (2nd ed.) that the two terms “are fundamentally synonymous.”

However, Black’s Law Dictionary (8th ed.), edited by Garner, has somewhat different definitions of “illegal” and “unlawful.”

The primary meanings of the two words are almost identical: “illegal” is defined as “forbidden by law; unlawful,” and “unlawful” is defined as “not authorized by law; illegal.”

But the “unlawful” entry in Black’s includes two additional senses: “criminally punishable” and “involving moral turpitude.”

Garner comments in A Dictionary of Modern Legal Usage that the additional senses “so complicate matters in using this term that they lessen its utility.”

That sounds to us as if he’s suggesting that lawyers avoid “unlawful” and use “illegal” when referring to something that’s “forbidden by law” or “not authorized by law.”

The early editions of Black’s Law Dictionary, edited by Henry Campbell Black, made more of the distinction between “illegal” and “unlawful.” The 1910 second edition, for example, describes the two terms this way:

 “ ‘Unlawful’ and ‘illegal’ are frequently used as synonymous terms, but, in the proper sense of the word, ‘unlawful,’ as applied to promises, agreements, considerations, and the like, denotes that they are ineffectual in law because they involve acts which, although not illegal, i.e., positively forbidden, are disapproved of by the law, and are therefore not recognized as the ground of legal rights, either because they are immoral or because they are against public policy. It is on this ground that contracts in restraint of marriage or of trade are generally void.”

The Oxford English Dictionary has nearly identical definitions of the two terms: “illegal” is defined as “not legal or lawful; contrary to, or forbidden by, law,” and “unlawful” as “contrary to law; prohibited by law; illegal.”

OED citations indicate that the older term, “unlawful,” showed up in English sometime before 1300, while “illegal” appeared in the early 1600s.

Interestingly, “unlawful” arrived on the scene about a century before “lawful,” according to the dictionary’s citations. “Illegal” arrived a century after “legal.”

Oxford says “illegal” comes from the French illégal or the medieval Latin illegalis, while the three parts of “unlawful” are derived from Old English. 

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