After graduating from Harvard College in 1823, he went to New York City, where he studied law under Chancellor James Kent and Vice-Chancellor William McCoun.

Dorr began his political career when elected as a representative in the Rhode Island General Assembly in 1834.

He became concerned about issues of the franchise: white men who were not allowed to vote because they did not own a certain value of real estate, and the dominance of rural interests in the state legislature, where seats were apportioned by geographic jurisdictions, with all towns being treated as equal.

In the half-century following the American Revolution, some activists worked to expand the franchise, often by reducing property or similar requirements.

Under that document, the original grantees had had the sole right to decide who should have a voice in the management of public affairs.

In 1840 the Rhode Island Suffrage Association was formed to address this increasingly unsatisfactory situation, and processions and popular meetings were held.

The legislature refused to remedy the grievances, and the old charter did not provide any means for citizens to convene a constitutional convention.

Feelings had become very bitter, and the Dorrites had already put their constitution into effect by electing an entire state ticket, with Dorr as governor.

A bungled attack on the Providence arsenal (which his father and younger brother, partisans of the "Law and Order" faction, were helping defend) led to the rebellion's disintegration.

Dorr returned briefly in June with a small band of New York volunteers and assembled an armed force of his followers on Acote's Hill in Chepachet.

The public was outraged about this sentence, and in 1845 the legislature passed an Act of General Amnesty; Dorr was released after serving twelve months of his term.

His work, however, bore fruit: in 1843 a third constitution had been drafted and ratified by the people that provided universal male suffrage.