a law unto himself, herself, etc.

a law unto (oneself)

Someone who does whatever they desire, ignoring the rules and regulations. If you need to delegate, I wouldn't ask Gina—she is a law unto herself, and it's hard to persuade her to do anything she's not interested in. How many times has Jason been arrested now? Geez, he sure is a law unto himself! The country will be met with swift sanctions if their president continues to act as a law unto himself.
See also: law, unto
Farlex Dictionary of Idioms. © 2022 Farlex, Inc, all rights reserved.

a law unto himˈself, herˈself, etc.

a person who does what they want, even when this is against the rules and customs of a group or society in general: That man is a law unto himself. He comes to work when he likes, and when he’s here he doesn’t do what he’s supposed to do.
See also: law, unto
Farlex Partner Idioms Dictionary © Farlex 2017
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