Elected as a supervisor, Mirkarimi received national attention in 2007 when he introduced the first legislation prohibiting the use of non-biodegradable plastic bags by large supermarkets and drugstores, making San Francisco the first city to do so.

He served from January to March 2012, at which time he was charged with domestic violence battery, child endangerment, and dissuading a witness in connection with a December 31, 2011 New Year's Eve altercation with his wife, and he was suspended from office pending an ethics investigation.

[9] While serving on the Board of Supervisors he changed his voter registration party affiliation to Democrat, acknowledging that he would be unable to advance in his political career as a registered Green.

"[11] As a San Francisco County supervisor, Mirkarimi sponsored some 40 pieces of legislation in a wide range of areas, including medical marijuana, crime, making streets safer for pedestrians, improving efficiency of city departments, and the environment.

[12] [13] In April 2009, he proposed legislation that would make San Francisco the first city in the nation to sell and distribute marijuana.

[15] In a speech accepting the award, he said, That particular logic (of being in favor of medicinal marijuana but not wanting dispensaries in the neighborhood in which you live), as complex as it is, was emblematic of what certainly concerned me, that we continue to drive back in the shadows the very idea of what we're all congregated here for, and that is to mainstream the issue so that marijuana should not be criminalized and medical cannabis should not be criminalized, and that we should do everything we can to build that kind of resiliency, to shore up even in the face of adversity, that while there's any attempt at pushback or blowback from our efforts to try to proliferate Prop 215 states throughout all fifty states of the United States, that we should not shrink at all with that ever particular kind of adversity once again.

"[17] On September 9, 2008, the San Francisco Board of Supervisors passed Mirkarimi's legislation creating a Reentry Council to coordinate the disparate and disconnected city programs that help ex-offenders transition from incarceration back into society.

[18][19] Mirkarimi, in collaboration with Public Defender Jeff Adachi, District Attorney Kamala Harris and Sheriff Michael Hennessey, crafted the legislation to increase the effectiveness of City-wide efforts to reduce recidivism and violence, and promote safe and successful reentry into society for adults released from jails and prisons.

[24] In July, he was one of several supervisors who, along with the mayor and various organizations, opposed a move to build fossil-fuel power plants in the low-income southeastern part of San Francisco.

[26] In 2008, Mirkarimi authored part of a reparations bill which would give descendants of those displaced by the San Francisco Redevelopment Agency from the Western Addition priority in obtaining affordable housing.

[27] In May 2011, scheduled to be termed out as supervisor, Mirkarimi announced he was running for sheriff of San Francisco in the November 2011 election.

"[29] In an interview with the Public Affairs Alliance of Iranian Americans (PAAIA), Mirkarimi said about his candidacy: The challenges of our campaign are that I am running citywide.

[28]Mirkarimi made combatting recidivism a centerpiece of his campaign: We have to realize that what happens in the jail system directly affects public safety throughout all of San Francisco neighborhoods.

That entwinement can't really be denied anymore, and the money we throw at the Police Department to just re-arrest the same people really sort of is counter-intuitive without asking the obvious question, "What can we do so that when somebody comes out they will not repeat their offense?"

[37] After his swearing-in ceremony, Mirkarimi suggested that the police probe was politically motivated,[38] and called the incident "a private matter.

[46] On July 20, 2012, Judge Garrett Wong lifted the stay away order originally issued in January 2012 that barred Mirkarimi from contacting his wife.

[47] On March 20, San Francisco Mayor Ed Lee gave Mirkarimi a 24-hour ultimatum to resign from his post as sheriff.

[5] In late July 2012 the National Lawyers Guild of San Francisco issued a statement urging the Board of Supervisors to support Mirkarimi and calling for an end to the use of City resources to pursue the case.

[50] Several groups also created statements of support for Mirkarimi to remain in office since the domestic violence allegations surfaced, including the San Francisco Labor Council.

[56] On April 23, 2012, misconduct hearings commenced at the San Francisco Ethics Commission to decide whether to recommend removing Mirkarimi from the sheriff's office.

[36][59][60] On August 16, the Commission ruled by 4 to 1 that Mirkarimi committed official misconduct by falsely imprisoning his wife, but delayed until September the decision to recommend whether he should be removed from office.

[62] The San Francisco Commission on the Status of Women recommended by a vote of 5 to 2 that the Board of Supervisors remove Mirkarimi as sheriff.

[66][67] Those who voted to reinstate Mikarimi were Supervisors David Campos, John Avalos, Jane Kim, and Christina Olague.

[68] Olague subsequently lost her seat as a supervisor of a progressive district to London Breed, due primarily to her vote[failed verification] to allow Mirkarimi to remain in office despite his pleading guilty to a domestic violence charge.

Campos lost a race in 2014 against fellow supervisor David Chiu for a seat in the State Assembly due in part to the Mirkarimi vote.

[69] On April 20, 2015, Mirkarimi filed a motion for dismissal and expungement with San Francisco Superior Court to remove his misdemeanor false imprisonment conviction from his criminal record.

Sheriff Mirkarimi reeling from scandal over forced fights," the San Francisco Chronicle suggested that Mirkarimi would have difficulty being re-elected in light of recent scandals in the Sheriff's Department — an escaped prisoner and a report that deputies in San Francisco County Jail had forced prisoners to fight each other for the guards' amusement.

[79] The San Francisco Chronicle opined, "A police officer slain in the line of duty is a disgrace that needs an answer.

The Board of Supervisors approved this measure, but Mayor Gavin Newsom, citing objections by Police Chief Heather Fong, vetoed it.

On January 7, 2017, Magistrate Judge Joseph C. Spero dismissed the family's claims of negligence and complicity against ICE and San Francisco.