(properly, the title in some jurisdictions) is the formal title appearing at the head of a statute (such as an Act of Parliament or of Congress) or other legislative instrument. The long title is intended to provide a summary description of the purpose or scope of the instrument; it contrasts with the short title, which is merely intended to provide a convenient name for referring to it.
Like other descriptive components of an Act (such as the preamble, section headings, side notes, and short title) the long title seldom affects the operative provisions of an Act, except where the operative provisions are unclear or ambiguous and the long title provides a clear statement of the legislature's intention.
In the United Kingdom, the long title is important since, under the procedures of Parliament, a Bill cannot be amended to go outside the scope of its long title. For that reason, modern long titles tend to be rather vague, ending with the formulation "and for connected purposes". The long title of an older Act is sometimes termed its rubric, because it was sometimes printed in red.
Short titles for Acts of Parliament were not introduced until the mid-19th century, and were not provided for every Act passed until late in the century; as such, the long title was used to identify the Act. Short titles were subsequently given to many unrepealed Acts at later dates; for example, the Bill of Rights (1688 or 1689) was given that short title by the Short Titles Act 1896, having until then been formally referred to only by its long title, An Act Declaring the Rights and Liberties of the Subject and Settling the Succession of the Crown. Similarly, in the US, the Judiciary Act of 1789, which was famously ruled unconstitutional in part by Marbury v. Madison, was called "An Act to establish the Judicial Courts of the United States".
The wording after "An Act" varies somewhat between jurisdictions. In some jurisdictions, including the United Kingdom, the long title opens with the words "An Act to ...". For example, the short title of the House of Lords Act 1999 is House of Lords Act 1999, but its long title is An Act to restrict membership of the House of Lords by virtue of a hereditary peerage; to make related provision about disqualifications for voting at elections to, and for membership of, the House of Commons; and for connected purposes. UK bills substitute the words "A Bill" for "An Act". Thus, before it passed, the long title of the House of Lords Bill 1999 was "A Bill to restrict membership...". Because of the way they are used to define the scope of bills, many British long titles are quite long.
While the long titles of most Acts of the US Congress read, "An Act to...", appropriations bills begin, "An Act making appropriations for...". Bills begin "A Bill for an Act..." Legislation in U.S. states also vary both in the exact wording and the level of detail of long titles. A typical long title in Illinois is, "AN ACT concerning safety", giving only a very broad characterization of the subject matter. On the other hand, a recent New Hampshire law carried the long title, "AN ACT relative to establishing a municipal bond rescission process, authorizing governing bodies to call a special meeting to consider reduction or rescission of appropriations, and clarifying special procedures enabling towns to respond appropriately to the American Recovery and Reinvestment Act of 2009."
Australian long titles are more like American than British ones in that they are short and broad: for example, "A Bill for an Act to provide for the establishment of the Automotive Transformation Scheme, and for related purposes". However, not all states use long titles and an Act may instead have an explicit "Purpose" section.
Long titles in South Africa omit the initial "An".