Johnston was admitted to the bar and began a law practice in Edenton. In 1759, he was elected to the
North Carolina House of Burgesses and served in that body until it was displaced in 1775 during the
American Revolution. During North Carolina's
War of the Regulation in December 1770, he introduced the anti-Regulators bill was later passed as the
Johnston Riot Act in response to the September 1770
Hillsborough Riot and to later reports of a planned Regulator march upon the provincial capital,
New Bern, which ultimately did not occur. The passage of the Johnston Riot Act and others precipitated an even more significant enlargement of the Regulator movement and forced
Royal Governor Tryon to call out the provincial militia, which culminated in the
Battle of Alamance on May 16, 1771. As a strong supporter of independence, he was also elected as a delegate to the first four
provincial congresses and presided over the Third and Fourth congresses in 1775 and 1776. After Royal Governor
Josiah Martin abdicated in 1775, he was the highest-ranking official in the state until
Richard Caswell was elected president of the Fifth Provincial Congress. Johnston is frequently cited as having served in the North Carolina Senate in 1779, but that is not confirmed in Senate Journals. He may have been elected, but he certainly did not attend. In Johnston's own words, after 1777, "...had nothing to do with public business..." during the Revolution. Under the new state government, Johnston was elected to the North Carolina Senate in 1783 and 1784. Johnston was the first Grand Master of Freemasons for the State of North Carolina, voted into office on 11 Dec 1787 to revive Masonic activities that had been defunct after breaking away from England. There had only been Deputy Grand Master until he was elected Grand Master. He would be elected Grand Master again in 1789-1791. ==Election as president==