In Bennett's youth, he was a follower of the Democratic Party, but a horseback tour in Fall 1842 of several southern states caused him to switch his allegiance.

[2] Questioning his previous politics, he followed the Barnburner faction of the Democratic Party, attending the 1848 convention in Buffalo that nominated Martin Van Buren for President of the United States.

[6] After the adoption of the constitution of California in November 1849, Bennett was elected a state senator from the district of San Francisco.

[10][11] In the winter of 1849–1850, he helped prepare the Senate Judiciary committee report to the Legislature on recommendations on adoption of the civil or common law.

[12] One commentator describes Bennett as one "whose decisions alone, among the early justices, show any considerable acquaintance with the Spanish Mexican system.

[25][26][27] At the convention, the Party nominated him to run again for the California Supreme Court on the same platform as Edward Stanly for governor, but he lost the 1857 election for Chief Justice to Stephen J.

[30] In 1859, while in Washington, he successfully argued before the Supreme Court of the United States the pueblo land grant case involving Rancho Corral de Tierra (Vasquez).

[38][39] In July 1869, continuing his interest in politics, his name was put forward at the state Republican convention to fill the Supreme Court vacancy from the retirement of Oscar L. Shafter.

[40] In October 1879, Bennett ran for Chief Justice of the California Supreme Court under the New Constitution Party, but garnered only one-third of the votes cast for the victor, Robert F.