idiom · To have a legitimate or sufficient reason to send troops or engage in military action.

古代统帅在出征前，总要列举对方的罪状，以求师出有名。

idiom · To do something with a valid reason or proper justification in general affairs.

他这次辞职可谓是师出有名，毕竟公司已经欠薪三个月了。