From Longman Dictionary of Contemporary Englishdouble standardˌdouble ˈstandard noun [countable] UNFAIRa rule, principle etc that is unfair because it treats one group of people more severely than another in the same situation
Examples from the Corpus
double standard• Jemmat's frank protest against a double standard is certainly unusual.• Society has a double standard when it comes to teen sex: it is seen as natural for boys but forbidden for girls.• This kind of governmental double standard towards minorities survived until the passing of the Race Relations Act in 1965.• That double standard was the underbelly of every easy laugh stand-up comedians got when they did hooker jokes.• Medical men, as well as the military and defenders of the double standard, were strong proponents of the Acts.• And at the other extreme, the success of social purity never silenced the defenders of the double standard. 