From Longman Dictionary of Contemporary Englishsit in judgment (on/over somebody)sit in judgment (on/over somebody)JUDGEto give your opinion about whether someone has done something wrong, especially when you have no right to do this How can you sit in judgment on somebody you hardly know? → sit
Examples from the Corpus
sit in judgment (on/over somebody)• Harrison presented himself and H-1 to the eight commissioners who sat in judgment of his work.• Certain Christians have also given the impression that they sit in judgment over others. 