1
general::
Phrase(s): in the wrong
wrong; morally or legally incorrect. • I am not in the wrong, you are. • No, you are in the wrong.
McGrawhill's American Idioms And Phrasal Verbs
2
general::
Mistaken, to blame. For example, The teacher was clearly in the wrong but refused to admit it, or Since he had driven straight through a red light, Jack was the one in the wrong. [c. 1400]
American Heritage Idioms