all’s fair in love and war

Any action, however mean or unscrupulous, is permissible in certain situations; often used to justify cheating or deception: “‘You opened the letter!’ . . . ‘How was I to read it if I hadn’t? All’s . . . fair in love and war, you know’” (Francis Edward Smedley, Frank Fairleigh, 1850). The proverb was first recorded, with different wording, in 1620. In modern use an extra word is often added to or substituted for part of the proverb, as in “All’s fair in love—an’ war—an’ politics” (George Ade, County Chairman, 1903).