A preamble is an introductory and explanatory statement in a document that explains the document's purpose and underlying philosophy. When applied to the opening paragraphs of a statute, it may recite historical facts pertinent to the subject of the statute. It is distinct from the long title or enacting formula of a law.

Legal effect

While preambles may be regarded as unimportant introductory matter, their words may have effects that may not have been foreseen by their drafters. For instance, it is on the basis of the preamble to the French Constitution, mentioning the solemn regard of the French Republic towards the principles set forth in the 1789 Declaration of the Rights of Man and of the Citizen that the Constitutional Council has declared certain laws to be unconstitutional (the first case being ). In Canada, the preamble to the Constitution Act, 1867 was cited by the Supreme Court of Canada in the Provincial Judges Reference, to increase guarantees to judicial independence. In India, the Supreme Court frequently rules unconstitutional amendments which, violate the Basic Structure of the Constitution, especially its Preamble. The preamble is just a cover page to the constitution.

Due to concern over its potential effects, the redaction of the preamble of the proposed European Constitution, in 2002, has caused much controversy because of the possible inclusion of a reference to the Christian heritage of Europe. Likewise, in Australia in 1998, a referendum on whether to adopt a new preamble was accompanied by a promise that the preamble, if adopted, could not be enforceable by the courts, as some were concerned with how the preamble could be interpreted and applied.