"It is legitimately within the scope of the legislature's investigatory power to inquire into the circumstances surrounding the termination (of) a public officer the legislature had previously confirmed," the judge wrote in his decision.
The probe is looking into whether Palin, who is the Republican vice presidential candidate, and others pressured Public Safety Commissioner Walt Monegan to fire a state trooper who was involved in a contentious divorce from Palin's sister, and then fired Monegan when he wouldn't dismiss the trooper. Palin says Monegan was ousted over budget disagreements.
The five Republican lawmakers had argued that the legislative body that ordered the investigation exceeded its authority. Their attorney, Kevin Clarkson, said the political bias was demonstrated by the plan of the Legislature's independent investigator to issue a report by Oct. 10 although the full legislature won't consider until reconvening in January.
But Michalski said in his ruling that the mere appearance of impropriety does not mean any individual's right to fairness was violated.
In the ruling, released minutes before Palin and Sen. Joe Biden faced off in a debate in St. Louis, Michalski agreed with defense attorney Peter Maassen, who argued that the Legislature has the authority to investigate the governor as it sees fit.
"He agreed with us on pretty much everything," Maassen said of the judge's ruling. "The separation of power principles that governed this case seemed pretty clear."
Maassen represents the Legislative Council, 10 Republicans and four Democrats who authorized the investigation, and others involved in the probe.
Clarkson did not immediately return a message left at his office.
At first, Palin agreed to cooperate with the probe, but since being picked Aug. 29 to be McCain's running mate, she, her family and staff have instead said the legislative investigation has been compromised by politics and that they would only cooperate with a separate investigation run by the Alaska State Personnel Board, whose members Palin can fire.
Michalski also threw out a lawsuit filed by Palin aides who had been subpoenaed to testify in the investigation. The aides had argued that the subpoenas should not have to be honored because they should not have been issued.
Todd Palin, the governor's husband, also refused to testify under subpoena, but he was not a plaintiff in the lawsuit filed by the state.