As corollary to the Townshend duties, the British tightened their supervision of colonial trade. The American Board of Customs Commissioners was created in 1767, raising the number of customs officials, constructing a colonial coast guard, and providing money to pay informers. However, the new board drew criticism due to its methods of enforcement. Like cases adjudicated under the Sugar Act, defendants were assumed guilty until they could prove otherwise. Informers were awarded one-third of all goods and ships confiscated from smugglers, an incentive to falsify charges and report shippers who committed even the slightest of offenses. Once the cases were transferred to vice-admiralty courts, they had a very high rate of conviction.
Customs officers enforced the duties vigorously and in underhanded manner, often relaxing certain technical restrictions for a time period and then suddenly clamping down. Customs officers would often claim that small items stored in a sailor's chest were undeclared cargo, and seize entire ships on that charge. The behavior of customs agents, often known as "customs racketeering," amounted to little more than legalized piracy. The activities of agents, and especially of informers, provoked considerable opposition from the colonists. Almost all cases of tarring and feathering during the years of the Townshend duties were instances of personal vengeance against informers. After 1767, riots led by sailors were increasingly common. Still, agents enforced the law strictly and tensions mounted.
In June 1768, John Hancock, the wealthiest of all Boston merchants, had a sloop, the Liberty, seized by customs agents on a perjured charge. A crowd of angry Bostonians formed, and tried to prevent the towing of the ship. Unsuccessful, they assaulted the customs agents in charge. The growing mob drove all of the revenue inspectors from the city.
By 1770, the British government began to reform the corrupt customs service. Charges against Hancock were dropped in fears that he would appeal to England, where honest officials would recognize the customs officers' deceit. In January 1770, Lord North became prime minister. He favored eliminating most of the Townshend duties to prevent a further split between the colonies and mother country. On April 12, 1770, Parliament did just this. However, Lord North insisted on maintaining the profitable tax on tea.
In response, Americans ended the policy of general non-importation, but maintained voluntary agreements not to consume British tea. Non-consumption kept the tea tax revenues far too low to pay the royal governors. The Townshend duties were effectively dead.
The behavior of the customs officials sent to enforce the Townshend duties convinced the colonists more than ever that their relationship with the British authorities had become one of enmity. The activities of informers and agents seemed to consist of petty needling at the colonists simply for the sake of antagonism, and as before, the colonists were outraged at the British concept of justice that accompanied the duties in the form of vice-admiralty courts.