at fault

noun

1. : a usually intentional act forbidden by law; also : a usually intentional omission to do something (as to exercise due care) required by law — see also negligence — compare no-fault, strict liability at liability : a usually intentional omission to do something (as to exercise due care) required by law — see also negligence — compare no-fault, strict liability at liability

   Note: Sometimes when fault is used in legal contexts it includes negligence, sometimes it is considered synonymous with negligence, and sometimes it is distinguished from negligence. Fault and negligence are the usual bases for liability in the law of torts.

2. : responsibility for an act or omission that causes damage or injury to another relative degrees of fault — see also comparative fault