James G. Maguire began his career as a blacksmith apprentice before transitioning to education, teaching school for a year and a half. He served in the California National Guard and played a role in suppressing the San Francisco Riots, demonstrating a commitment to public order. Maguire was admitted to the bar in 1878 and subsequently served as a judge for the San Francisco County Superior Court. He held political roles in the California State Assembly and sought various judicial and legal positions, including nominations for city attorney and judge. Maguire's political affiliations shifted between the Democratic Party and the United Labor Party, reflecting his evolving stance on labor rights and economic justice.

James G. Maguire's political identity is marked by an ideological fluidity that oscillates between labor rights and economic justice, as seen in his alignment with Henry George's United Labor Party, and a commitment to maintaining public order through his military service. His early involvement in education and later judicial roles suggest a nuanced approach to policy, balancing idealism with pragmatism. Maguire's departure from and return to the Democratic Party reveal a strategic disenchantment with party bosses, hinting at a deeply personal, perhaps principled, political journey.