A double standard is the application of different sets of principles for situations that are, in principle, the same. It is often used to describe treatment whereby one group is given more latitude than another. A double standard arises when two or more people, groups, organizations, circumstances, or events are treated differently even though they should be treated the same way. A double standard "implies that two things which are the same are measured by different standards".

Applying different principles to similar situations may or may not indicate a double standard. To distinguish between the application of a double standard and a valid application of different standards toward circumstances that only appear to be the same, several factors must be examined. One is the sameness of those circumstances – what are the parallels between those circumstances, and in what ways do they differ? Another is the philosophy or belief system informing which principles should be applied to those circumstances. Different standards can be applied to situations that appear similar based on a qualifying truth or fact that, upon closer examination, renders those situations distinct (a physical reality or moral obligation, for example). However, if similar-looking situations have been treated according to different principles and there is no truth, fact or principle that distinguishes those situations, then a double standard has been applied.

If correctly identified, a double standard usually indicates the presence of hypocrisy, bias or unjust behaviors.