No, it is not--the law does not require checking ID before accepting a check. There are situations where it would be negligent (unreasonably careless) to not check  ID--for example, the check is in a male name, but the person is female; the check is in an obviously Asian name, but the person is caucasion; etc.--and in those situations there might be liability for a failure to check ID. The store also does need to cooperate with you in investigating the theft; and the first thing yiou should do is to tell your bank that the check was cashed by someone else and see if they can stop or reverse it.