have the law of

lay down the law

To authoritatively or dogmatically assert what is permitted or not permitted.

lemon law

A law dealing with defective items, especially automobiles, and the rights of consumers.

long arm of the law

The influence or effectiveness of law enforcement institutions; law enforcement officers collectively.

one's word is law

One's requests or orders must be fulfilled.

take the law into one's own hands

To punish someone according to one's own idea of justice, without consideration for the role of law enforcement authorities.