Gansler took office as Maryland's attorney general in January 2007, after winning election in November 2006. He was re-elected on November 2, 2010. Gansler declined to seek a third term as attorney general in 2014, deciding to run for governor instead. He was defeated in the 2014 Democratic gubernatorial primary.

Minimum wage increase

In the fall of 2013, Gansler said he supported an increase in the state minimum wage. Among the biggest supporters of mandatory higher pay was state Rep. John Delaney (D-6) who pledged to put his own personal funds behind a campaign to raise the minimum wage state-wide. On September 6, Gansler urged an increase in the minimum wage from $7.25 to $10 per hour. "Clearly the time has come to raise the minimum wage here in Maryland," Gansler said. "While the economy shows signs of recovery, too many working families are struggling."

Protecting Financial Aid for Students and Taxpayers Act

On March 11, 2013, Gansler, together with 12 other state attorneys general, sent a letter to Congress in support of the Protecting Financial Aid for Students and Taxpayers Act, a bill that sought to ban for-profit colleges from using federal funds for marketing and recruiting techniques. Senators Kay R. Hagan (D-NC) and Tom Harkin (D-Iowa), who chaired the chamber's Health, Education, Labor, and Pensions Committee, sponsored the bill. Massachusetts Attorney General Martha Coakley (D) stated that the proposed law aimed to “ensure that scarce federal education dollars will be used to serve and educate students rather than to finance advertising campaigns, recruitment operations, and aggressive marketing.”

In the letter, the attorneys general wrote, “Federal taxpayers should not be asked to foot the bill for aggressive recruiting and deceptive sales tactics of colleges that have placed profits ahead of ensuring student success.” At the time, there were an estimated 3,000 for-profit schools nationwide, though neither the letter nor the bill cited the name of any specific institutions.

On March 12, 2013, the bill was referred to the Senate Committee on Health, Education, Labor, and Pensions, but no subsequent action was taken and the bill died in committee. On April 23, 2013, a related bill—HR 340—was referred to the House Committee on Education and the Workforce's subcommittee on Higher Education and Workforce Training, but it also died in committee.

ACORN

The June 2008 Survey and Scorecard report published by the liberal political organization, ACORN, gave Gansler an A letter grade. The report was published to highlight state attorneys general "leading the fight to protect homeowners from joining the flood of Americans losing their homes to foreclosure," according to the group. The grade distributed to the individual attorneys general "generally broke down along party lines," with the exception of Louisiana's Buddy Caldwell.

Same-sex marriage

On February 25, 2010, Gansler published an opinion that stated that "there is no law in Maryland that says we don't recognize out-of-state marriages between same-sex couples." This, in effect, required state agencies to extend all benefits given to married heterosexual couples to married gay couples. At the same time, however, this ruling did not apply to private industries nor did it suggest that state law permitted same-sex marriage.

Impeachment attempt

As a result of Gansler's February 2010 legal opinion, in which he argued that state courts must recognize same-sex marriages performed in other states, an inquiry led by Republican state Del. Don Dwyer, Jr. was made as to whether or not the state house had the authority to impeach the state's attorney general. Dwyer and his supporters argued that the line in Article III of the state constitution, in which it stated that "the Maryland House of Delegates shall have the sole power of impeachment in all cases," gave the state legislative body that power. Others argued there was a conflict within the state constitution on this particular issue, pointing out another provision which said that the state attorney general "shall be subject to removal for incompetency, willful neglect of duty or misdemeanor in office, on conviction in a Court of Law."

Democratic House Speaker Michael Busch appointed a Democratic delegate as parliamentarian to interpret the rules for the state house. In response, Dwyer filed an ethics complaint against Busch for not delegating the position to a staff member, as was done in other legislatures. On Wednesday, March 31, 2010, the State House Judiciary Committee voted 15-5 against taking such action against Gansler, contending that his legal opinion "did not merit impeachment proceedings."

Gansler served as State's Attorney for Montgomery County, Maryland, from January 1999 to January 2007. During his tenure, his office prosecuted noteworthy cases including the Beltway snipers, John Muhammad, and Lee Boyd Malvo. In 1999, the office became the first in the country to use community prosecution, where "office staff was reorganized according to geographical lines. All attorneys, while maintaining their centrally located office, [were] assigned to one of the five police districts, with staffing proportionate to the number of cases in each of the districts." According to the Maryland Governor's Office of Crime Control & Prevention, Gansler "established the first domestic violence dockets, gang unit, internet crime unit, and Elder Abuse Task Force in Maryland."

In 2002, the Maryland Court of Appeals reprimanded him for "statements regarding a criminal defendant’s possibility of a plea of guilty, another criminal defendant’s confession, and his opinion as to the guilt of two criminal defendants" in several cases. He was the first elected Maryland State's Attorney to be reprimanded by the court and the first attorney in the state of Maryland to be reprimanded for violating Meritorious Claims and Contentions, 3.6 (Trial Publicity). Speaking to The Daily Record, Gansler's attorney said, "the court is placing unnecessary restraints upon prosecutors who need to be able to communicate with the community during investigations where public safety is in doubt."

In the fall of 2013, Gansler said he supported an increase in the state minimum wage. Among the biggest supporters of mandatory higher pay was state Rep. John Delaney (D-6) who pledged to put his own personal funds behind a campaign to raise the minimum wage state-wide. On September 6, Gansler urged an increase in the minimum wage from $7.25 to $10 per hour. "Clearly the time has come to raise the minimum wage here in Maryland," Gansler said. "While the economy shows signs of recovery, too many working families are struggling."

On March 11, 2013, Gansler, together with 12 other state attorneys general, sent a letter to Congress in support of the Protecting Financial Aid for Students and Taxpayers Act, a bill that sought to ban for-profit colleges from using federal funds for marketing and recruiting techniques. Senators Kay R. Hagan (D-NC) and Tom Harkin (D-Iowa), who chaired the chamber's Health, Education, Labor, and Pensions Committee, sponsored the bill. Massachusetts Attorney General Martha Coakley (D) stated that the proposed law aimed to “ensure that scarce federal education dollars will be used to serve and educate students rather than to finance advertising campaigns, recruitment operations, and aggressive marketing.”

In the letter, the attorneys general wrote, “Federal taxpayers should not be asked to foot the bill for aggressive recruiting and deceptive sales tactics of colleges that have placed profits ahead of ensuring student success.” At the time, there were an estimated 3,000 for-profit schools nationwide, though neither the letter nor the bill cited the name of any specific institutions.

On March 12, 2013, the bill was referred to the Senate Committee on Health, Education, Labor, and Pensions, but no subsequent action was taken and the bill died in committee. On April 23, 2013, a related bill—HR 340—was referred to the House Committee on Education and the Workforce's subcommittee on Higher Education and Workforce Training, but it also died in committee.

The June 2008 Survey and Scorecard report published by the liberal political organization, ACORN, gave Gansler an A letter grade. The report was published to highlight state attorneys general "leading the fight to protect homeowners from joining the flood of Americans losing their homes to foreclosure," according to the group. The grade distributed to the individual attorneys general "generally broke down along party lines," with the exception of Louisiana's Buddy Caldwell.

On February 25, 2010, Gansler published an opinion that stated that "there is no law in Maryland that says we don't recognize out-of-state marriages between same-sex couples." This, in effect, required state agencies to extend all benefits given to married heterosexual couples to married gay couples. At the same time, however, this ruling did not apply to private industries nor did it suggest that state law permitted same-sex marriage.

As a result of Gansler's February 2010 legal opinion, in which he argued that state courts must recognize same-sex marriages performed in other states, an inquiry led by Republican state Del. Don Dwyer, Jr. was made as to whether or not the state house had the authority to impeach the state's attorney general. Dwyer and his supporters argued that the line in Article III of the state constitution, in which it stated that "the Maryland House of Delegates shall have the sole power of impeachment in all cases," gave the state legislative body that power. Others argued there was a conflict within the state constitution on this particular issue, pointing out another provision which said that the state attorney general "shall be subject to removal for incompetency, willful neglect of duty or misdemeanor in office, on conviction in a Court of Law."

Democratic House Speaker Michael Busch appointed a Democratic delegate as parliamentarian to interpret the rules for the state house. In response, Dwyer filed an ethics complaint against Busch for not delegating the position to a staff member, as was done in other legislatures. On Wednesday, March 31, 2010, the State House Judiciary Committee voted 15-5 against taking such action against Gansler, contending that his legal opinion "did not merit impeachment proceedings."

Montgomery County State's Attorney (1998-2006)

Gansler served as State's Attorney for Montgomery County, Maryland, from January 1999 to January 2007. During his tenure, his office prosecuted noteworthy cases including the Beltway snipers, John Muhammad, and Lee Boyd Malvo. In 1999, the office became the first in the country to use community prosecution, where "office staff was reorganized according to geographical lines. All attorneys, while maintaining their centrally located office, [were] assigned to one of the five police districts, with staffing proportionate to the number of cases in each of the districts." According to the Maryland Governor's Office of Crime Control & Prevention, Gansler "established the first domestic violence dockets, gang unit, internet crime unit, and Elder Abuse Task Force in Maryland."

In 2002, the Maryland Court of Appeals reprimanded him for "statements regarding a criminal defendant’s possibility of a plea of guilty, another criminal defendant’s confession, and his opinion as to the guilt of two criminal defendants" in several cases. He was the first elected Maryland State's Attorney to be reprimanded by the court and the first attorney in the state of Maryland to be reprimanded for violating Meritorious Claims and Contentions, 3.6 (Trial Publicity). Speaking to The Daily Record, Gansler's attorney said, "the court is placing unnecessary restraints upon prosecutors who need to be able to communicate with the community during investigations where public safety is in doubt."