[5] Bratton's appointment is widely seen as leading to the sharp declines in Los Angeles' crime rate and improved morale in the department.

While he is noted primarily for these two accomplishments, they also helped lead to his unsuccessful re-election bid; African Americans upset at Parks' ousting and San Fernando Valley residents disappointed with the secession verdict had been the two constituencies that had propelled him to victory four years earlier in 2001.

[11] He graduated from the Los Angeles campus of Pepperdine University in California magna cum laude with a bachelor's degree in English and a minor in journalism in 1972.

During Hahn's tenure, he led the litigation to stop the Joe Camel ad campaign and reached a settlement of 312 million dollars for the city.

[16] In 2002, Mayor Hahn rejected Bernard Parks for a second term as Los Angeles police chief and appointed former NYPD Commissioner William Bratton to the position.

[21] As a result, the LAPD experienced an increase in its ranks, morale significantly rose throughout the department and all areas of crime dropped steadily.

[24] To better prepare the city for future emergencies, Hahn convened a Homeland Security cabinet in his office,[25] coordinated Los Angeles' "Operation Archangel" to protect its infrastructure[26] and lobbied for state and federal public safety grants.

[34] Mayor Hahn created a $100 million affordable housing trust fund, which was at the time the nation's largest,[35][36] and expanded the adaptive reuse ordinance to convert dilapidated buildings into mixed-use residential properties.

[40] Hahn led two trade missions as Mayor, the first to Mexico in 2001, and the second to Asia in 2002, where he visited Japan, China, South Korea and Taiwan.

[45] Other agreements made the Los Angeles Zoo the first in the United States to exhibit a pair of Chinese golden monkeys,[46] regionalized air service by shifting Taiwan-based EVA Airlines' operations to Ontario International Airport, and improved air quality by plugging more Asian cargo ships into natural power while docked at the Port of Los Angeles.

Choices included Ray Bradbury's Fahrenheit 451 in 2002,[53] Sandra Cisneros' House on Mango Street in 2003, and Laura Hillenbrand's Seabiscuit in 2004.

[68] On October 19, 2005, Hahn took part in a discussion entitled "The State of Los Angeles", sponsored by a non-profit organization called "Days of Dialogue".

"Days of Dialogue" was founded after the notorious O. J. Simpson trial in order to encourage discussions on key issues in the Los Angeles region.

[70] On September 20, 2006, more than a year after leaving office, a Steve Lopez column ran in the Los Angeles Times explaining Hahn's new life in the private sector.

He also enjoys his new work getting unions to invest money in local projects around transit lines to relieve traffic and smog.

[72] On November 5, 2008, Schwarzenegger appointed Hahn to fill a vacant judgeship in the Los Angeles County Superior Court.

[75] In 2017, Hahn again joined former Mayors Richard Riordan and Antonio Villaraigosa for a moderated conversation as part of the University of California, Los Angeles's "Why History Matters" series.