at fault

Idioms  

1. Responsible for a mistake, trouble, or failure; deserving blame. For example, At least three cars were involved in the accident, so it was hard to determine which driver was at fault, or He kept missing the target and wondered if the sight on his new rifle was at fault. In Britain this usage was formerly considered incorrect but is now acceptable; in America it has been widespread since the mid-1800s. Also see in the wrong.

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Example Sentences

It looks like he's at fault for the first goal but it's actually Antonee Robinson running out to the left for no good reason.

From BBC

She added women may accept one miscarriage as bad luck, but when it happens again they frequently start to wonder if they are somehow at fault.

From BBC

But her dream debut was quickly tarnished as Brazil went 2-0 up within 18 minutes, putting England on the ropes - though Keating was not at fault.

From BBC

Brenda remains steadfast: In addition to a proper cash settlement, she insists on receiving an apology and a promise the firm at fault will remedy its harmful program.

From The Wall Street Journal

County collisions in which a law enforcement vehicle was found to be at fault have risen steadily.

From Los Angeles Times