ANCHORAGE, Alaska — Gov. Sarah Palin's administration is threatening legal action to block any subpoenas by the Alaska Legislature as part of its investigation into whether she abused her authority in trying to have her former brother-in-law fired as a state trooper.

In a letter to lawmakers, an assistant attorney general wrote that the administration was prepared to go to court to quash the subpoenas of Department of Administration staff if they're issued as expected today. The investigation, known as "Troopergate," took on new significance after Sen. John McCain, the GOP presidential nominee, selected Palin as his running mate.

However, the letter also suggested that if lawmakers agree that the governor has legal authority to designate staff to review confidential personnel files, the staff members will voluntarily speak with the Legislature's investigator — no subpoenas necessary.

"If the Legislative Council will acknowledge in writing its agreement ... the Department of Law will drop its objections and the depositions may proceed without subpoenas," Senior Assistant Attorney General Michael Barnhill wrote in the letter, which was dated Tuesday and released Thursday.

Sen. Kim Elton, who chairs the Legislative Council, was on a plane and could not be reached for comment Thursday. An aide, Jesse Kiehl, said: "He's read the letter. I don't believe that we have written back."

The council voted unanimously in July to launch an investigation into whether Palin fired her public safety commissioner because he refused to fire Trooper Mike Wooten, who went through a messy divorce from Palin's sister. The issue, essentially, is whether Palin used her power try to settle a personal score.

Palin has said the commissioner, Walt Monegan, was fired over disagreements about budget priorities.

Early this month, Sen. Hollis French, the Democrat who heads the Senate Judiciary Committee, was quoted in a news report as saying that if the governor's office obtained confidential information from Wooten's personnel file "it would be a violation of state law."

The attorney general's office disagrees with that interpretation and says the governor, as the employer of state workers, can designate her staff to review confidential files. Barnhill called French's statement "an improper threat of potential prosecution" that was "totally inconsistent" with the state constitutional right to fair and just treatment in legislative and executive investigations.

Barnhill added that if any administration officials disclosed information from Wooten's personnel file to people outside the administration, that could violate the State Personnel Act.

"At this point, the Department of Law knows of no evidence that suggests that any Department of Administration employees violated the State Personnel Act in handling Trooper Wooten's personnel file," he wrote.

One administration official, Frank Bailey, was recorded calling an Alaska State Troopers lieutenant and discussing confidential information about Wooten. In a deposition taken by Palin's attorney, he testified that he never saw Wooten's file, but instead received the information from the governor's husband, Todd Palin.

On the advice of Barnhill and their own attorneys, Bailey and six other witnesses canceled their scheduled depositions following French's statement. French responded by promising to issue subpoenas.

The House and Senate Judiciary Committees were scheduled to hold a joint meeting Friday to decide whether to issue them. A majority of either committee can do so.