A writ of assistance is a written order (a writ) issued by a court instructing a law enforcement official, such as a sheriff or a tax collector, to perform a certain task. Historically, several types of writs have been called "writs of assistance". Most often, a writ of assistance is "used to enforce an order for the possession of lands". When used to evict someone from real property, such a writ is also called a writ of restitution or a writ of possession. In the area of customs, writs of assistance were first authorized by an act of the English Parliament in 1660 (12 Charles 2 c. 29), and were issued by the Court of Exchequer to help customs officials search for smuggled goods. These writs were called "writs of assistance" because they called upon sheriffs, other officials, and loyal subjects to "assist" the customs official in carrying out his duties.
In general, customs writs of assistance served as general search warrants that did not expire, allowing customs officials to search anywhere for smuggled goods without having to obtain a specific warrant. These writs became controversial when they were issued by courts in British America in the 1760s, especially the Province of Massachusetts Bay. Controversy over these general writs of assistance inspired the Fourth Amendment to the United States Constitution, which forbids general search warrants in the United States.
General writs of assistance played an important role in the increasing tensions that led to the American Revolution and the creation of the United States of America. In 1760, Great Britain began to enforce some of the provisions of the Navigation Acts by granting customs officers these writs. In New England, smuggling had become common. However, officers could not search a person's property without giving a reason. Colonists protested that the writs violated their rights as British subjects. The colonists had several problems with these writs. They were permanent and even transferable; the holder of a writ could assign it to another. Any place could be searched at the whim of the holder, and searchers were not responsible for any damage they caused. This put anyone who had such a writ above the laws.