Even before the French and Indian War ended, the British decided to heighten their level of control over trade in the colonies. Colonial assemblies had proven unable to stem trade with the French West Indies, and certain ports, such as Boston and Newport, Rhode Island, engaged heavily in trade with the enemy in the West Indies. Colonial smugglers that traded with the West Indies, not only sustained the enemy, but avoided duties imposed by the Molasses Act of 1733. The Molasses Act charged a duty of six pence a gallon on molasses, nine pence on a gallon of rum, and five shillings per 100 pounds of sugar on goods imported from non-British territories. Smuggling thus not only aided Britain's wartime enemy, but also deprived the British treasury of much needed revenue during the war.
In response, the British officials in the colonies called for a crackdown on smuggling. In 1760, governor Bernard of Massachusetts authorized the use by revenue officers of writs of assistance. Writs of assistance were documents which served as a general search warrant, allowing customs officials to enter any ship or building that they suspected for any reason might hold smuggled goods.
Writs of assistance proved an immediately useful tool in the fight against smuggling, and many buildings and ships were ransacked and seized. Shortly after their implementation, Boston merchants, the group primarily responsible for smuggling in the colonies, hired lawyer James Otis to challenge the constitutionality of the writs before the Massachusetts supreme court, which he did in 1761, in what is known as the Petition of Lechmere. A fiery orator, Otis argued that the writs were "against the fundamental principles of law," and claimed that even an act of Parliament "against the Constitution is void." It took two and a half years before the ruling in the case was delivered. After consulting extensively with authorities in Britain, and noting the use of similar writs in England, the court, heavily influenced by the opinions of Chief Justice Thomas Hutchinson, ruled against the Boston merchants and kept the writs in place.
The writs of assistance and Otis' arguments at trial convinced many that Britain had overstepped its bounds, and objections to their use was commonly heard at town meetings and in assemblies throughout the colonies. However, political opposition to the writs ended with the Boston merchants' loss in the Petition of Lechmere. It would take further impositions by the British government before the colonists would begin to truly question parliamentary authority.
Smuggling was a major problem in the American colonies during and after the war. It is clear that if there had been no smuggling the British government would have taken in more revenue from customs duties. Additionally, later evidence has shown that the influx of goods to the French West Indies provided by American smugglers was a primary reason the French were able to sustain their war effort in North America for as long as they did. During the war it was well known that smuggling accounted for a significant part of American income, but in the midst of the fighting the British found it nearly impossible to regulate trade effectively. Thus, partially because they had few other options and partially out of frustration and anger, the writs of assistance were granted and used.
Despite the assertion by the Massachusetts supreme court that the writs of assistance were within legal limits, most English authorities agreed that the writs violated the Constitution. Colonists and Many British observers were outraged at the blatant neglect of what had been traditionally considered British liberties. Most notably, the writs allowed officials to enter and ransack private homes without proving probable cause for suspicion, a traditional prerequisite to a search.
Although he lost the case against the writs of assistance, James Otis hit upon precisely the ideological cornerstone that would lead the colonies up to and into revolution. The British Constitution was not a written document; it was an unwritten collection of customs and traditions guaranteeing certain rights, and therefore an abstract and fungible thing. Most British subjects assumed that all laws made by Parliament were incorporated into the Constitution, and thus that Parliament could alter the Constitution as it wished, without question. The government was the sole judge of the constitutionality of its actions. However, Otis' primary argument in front of the supreme court centered on the growing sentiment in the colonies that even Parliament could not infringe on certain basic rights that stood at the core of the Constitution, often termed 'the rights of Englishmen.' Otis contended that in the principles of government, there existed certain limits, "beyond which if Parliaments go, their Acts bind not." This claim echoed the growing conception of the great majority of colonists as to the proper role of Parliament under the British Constitution. In the years to come, the colonists continued to complain that the British government had infringed upon this set of "inalienable" rights. This infringement was commonly claimed as the motive for revolution.