Peter Oliver combined industrial activity and office in colonial Massachusetts. Without formal legal training, he entered the local magistracy as a justice of the peace in 1744 and became a judge of the Plymouth County inferior court. He also represented Middleborough in the legislature and served on the provincial council. These roles joined local standing with participation in the administration of royal government.

Appointed to the Superior Court in 1756, he rose to chief justice in 1772. His surviving notes on the trial of British soldiers after the Boston Massacre record his involvement in one of the colony's most politically charged proceedings. They are evidence of courtroom work as well as of the difficulty of maintaining judicial authority amid conflict between imperial officials and colonial opponents.

The question of judicial salaries made him a direct target. British payment of judges was intended to free the bench from dependence on the colonial assembly, but critics saw it as making judges dependent on the Crown. Oliver refused to renounce the royal salary when other judges did so. In 1774 the Massachusetts House adopted articles of impeachment against him, drawing on arguments developed by John Adams and other opponents of the arrangement.

The proceeding did not produce a completed trial and judgment removing him. Instead, Governor Hutchinson's refusal to preside prevented action in the council, while jurors refused to serve with Oliver on the bench. His effort to continue sitting exposed the collapse of practical authority even before royal judicial government formally ended. A committed Loyalist, he later left Massachusetts and spent his final years in Britain. His account of the Revolution, Origin and Progress of the American Rebellion, defended the royal side and attacked its opponents. It remains a partisan source. A salary dispute had become a contest over colonial justice, turning a judge into a symbol of a government many would no longer obey.