A double standard is the application of different sets of principles for similar situations, or by two different people in the same situation. 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. The phrase "life is not fair" may be invoked in order to mollify concerns over double standards.
Examples of Double-Standard in Action 
(Taken from the Main Article: Male-female income disparity in the United States): One supposed example of a double-standard being applied is the apparent inequity of pay between male and female workers in similar positions. Male–female income difference, also referred to as the "gender gap in earnings" in the United States, refers usually to the ratio of female to male median yearly earnings among full-time, year-round (FTYR) workers. In 2010 the median income of FTYR workers was $42,800 for men, compared to $34,700 for women. The female-to-male earnings ratio was 0.81, slightly higher than the 2008 ratio. The female-to-male earnings ratio of 0.81 means that, in 2009, female FTYR workers earned 19% less than male FTYR workers. The statistic does not take into account differences in experience, skill, occupation, education or hours worked, as long as it qualifies as full-time work. However, in 2010, an economist testified to the U.S. Congress Joint Economic Committee that studies "always find that some portion of the wage gap is unexplained" even after controlling for measurable factors that are assumed to influence earnings. The unexplained portion of the wage gap is sometimes attributed to gender discrimination. A double-standard is purported by some to be to blame for the lower average income of women in the United States.
See also 
- "Double standard" Dictionary.com
- "Unjust Judgments on Subjects of Morality". The Ecclesiastical Observer (London: Arthur Hall and Co.) XXV: 167–170. April 1, 1872.
- Josephine E. Butler (Nov. 27, 1886). "The Double Standard of Morality". Friends' Intelligencer and Journal (Philadelphia: Friends' Intelligencer Association). XLIII (48): 757–758.
- "BC Liberals accused of salary 'double standard'" www.CBC.ca