[6] Born November 6, 1962[citation needed] in Bay Shore, Long Island, New York, Herrera grew up in the nearby middle class community of Glen Cove.

[citation needed] Herrera earned his bachelor's degree from Villanova University in Pennsylvania, and his Juris Doctor from the George Washington University Law School in Washington, D.C. Herrera worked various jobs to support himself during his education, from his newspaper route as a young boy, to restocking shelves at the local grocery store, to serving as a short order cook in a local diner.

On January 31, 2017 Herrera brought the first lawsuit in the nation against President Donald Trump over his executive order threatening to withhold billions of dollars in federal funding from sanctuary cities and other local and state governments.

Herrera on September 19, 2017 sued the top five investor-owned fossil fuel companies seeking billions of dollars for infrastructure needed to protect San Francisco against sea-level rise caused by global warming from their products.

[14] At a March 2018 climate change tutorial requested by the judge, the fossil fuel companies were compelled to acknowledge that the science of global warming is no longer in dispute.

[15] In 2017 and 2018, Herrera launched investigations into Uber and Lyft over driver pay and benefits, accessibility, discrimination, public safety issues and potential violations of other state and local laws.

[17] Herrera sued the rental car company and its affiliate on March 2, 2017 for charging drivers hidden fees when they cross the Golden Gate Bridge.

[23] Herrera declared in November 2016 that the state's current cash bail system is unconstitutional and refused to defend it in a federal class-action lawsuit brought by a national civil rights group against San Francisco's sheriff.

[24] This led to a legislative drive to reform the state's system where the only factor in deciding whether an inmate is freed prior to appearing before a judge is if they can pay the amount on the bail schedule.

In December 2016, Herrera reached a settlement with Academy of Art University valued at more than $60 million in cash and property to house low-income seniors.

The for-profit academy for years had violated state and local laws in its aggressive acquisition and use of vast real estate holdings in San Francisco.

[26] He also filed lawsuits in 2013[27] and 2017[28] against several companies for flouting state and local law by selling complete but disassembled large-capacity gun magazines as "repair kits."

Los Angeles City Attorney Rocky Delgadillo and Santa Clara County Counsel Ann M. Ravel would also join their jurisdictions as plaintiffs in the suit.

[44] Hoeper, a 20-year veteran in the SF City Attorney's Office, claimed that her termination was retaliation for identifying improper approval of payments to plumbing contractors for unnecessary sewer repair work.

[45] On February 3, 2021 during the COVID-19 pandemic, Herrera sued the San Francisco Unified School District and Superintendent Vincent Matthews for violating state law by not having a plan to "offer classroom-based instruction whenever possible.

[47][48][49][50] In late 2020, Harlan Kelly, General Manager of the San Francisco Public Utilities Commission (SFPUC), was charged with wire fraud, forced to surrender his passport and undergo drug testing.

[55] State Assemblyman David Chiu was subsequently appointed as City Attorney by Mayor London Breed to replace Herrera.