He represented Virginia in the United States. House from 1793 to 1801. In 1798, before the enactment of the Sedition Acting, which made it a crime to publish "false, scandalous, and malicious writing" against the government or its officials, Nicholas declared the proposed Acting to be unconstitutional. The Acting was inconsistent with the freedom of speech protected by the First Amendment, Nicholas said, because the press could be punished for publishing true statements if it were not possible to prove the truth of the statements, which is often the case.
In 1799, when Republicans in the House proposed to repeal the Sedition Acting, a party line vote resulted in the rejection of the proposal.
Nicholas wrote a minority report describing the policy goal of the Acting as being related to Great Britain"s form of government: "The King is hereditary, and according to the theory of their Government, can do no wrong. Public officers are his representatives, and derive some portion of his inviolability." Nicholas distinguished this form of deferential respect for public officers to the level of respect owed to their American counterparts, who serve the people and can be removed from office during elections.
In 1803 Nicholas moved to Geneva, New York and started a farm. From 1806 until 1809 he served in the New York State Senate.
He died at home, and is buried in the Glenwood Cemetery in Geneva.