lettre de cachet (lĕ`trə də käshā`), formerly in French law, private, sealed document, issued as a communication from the king. Such a letter could order imprisonment or exile for an individual without recourse to courts of law. Of very early origin, the lettre de cachet came into common use in the 17th cent. as an instrument of the new monarchy. Although its actual use was restrained, the issuance to local officials of lettres de cachet with the space for the name left blank inspired great fear. The occasional invocation of them against leaders of opinion, including Voltaire, became a symbol of arbitrary royal power and tyranny. They were abolished by the Constituent Assembly in the French Revolution. Napoleon I briefly renewed use of the lettres de cachet.