[2] He served as a Lieutenant in the California National Guard in 1877,[4] during which he was called upon to help suppress the San Francisco Riots.

[6] He studied law and was admitted to the Bar by the Supreme Court of California in January 1878, commencing practice in San Francisco.

[7] The next year, he was elected a judge of the Superior Court of the City and County of San Francisco, serving from 1882 to 1888.

[8] In the 1898 state elections, Maguire unsuccessfully ran as the Democratic candidate for Governor of California, losing to Republican Henry Gage.

He ran for public office one last time, running for District Attorney of San Francisco in 1911 but losing in the primary to incumbent Charles Fickert.