双重标准是指针对某一种特定行为，因实施的人不同，而导致评价褒贬不一的现象。也就是说，某一群体或个人被允许实施某一种行为，但另外一群体或个人却被禁止实施该行为。双重标准是一种人与人之间的偏见或歧视，违反了公正、平等的原则。但实行“双重标准”的人常在口头上则称自己很公平；而对于某种事态因时代、环境等外部条件不同，而以两个不同的标准处理时，也可能被指责为「双重标准」。

能够表达“双重标准”意思的词句如「选择性执法」、「只许州官放火，不准百姓点灯」等；劝诫避免「双重标准」的词句如「正人先正己」、「以身作则」等。

A double standard is the application of different sets of principles for similar situations.

A double standard may take the form of an instance in which certain concepts (often, for example, a word, phrase, social norm, or rule) are perceived as acceptable to be applied by one group of people, but are considered unacceptable—taboo—when applied by another group. A double standard can therefore be described as a biased or morally unfair application of the principle that all are equal in their freedoms. Such double standards are seen as unjustified because they violate a basic maxim of modern legal jurisprudence: that all parties should stand equal before the law. Double standards also violate the principle of justice known as impartiality, which is based on the assumption that the same standards should be applied to all people, without regard to subjective bias or favoritism based on social class, rank, ethnicity, gender, religion, sexual orientation, age, or other distinctions. A double standard violates this principle by holding different people accountable according to different standards.