Judge Peter Michalski heard from both sides in the fight over the Alaska Legislature's investigation but did not rule immediately. Attorneys in the case expected a decision later in the day.
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.
Five Republican state lawmakers argued that the legislative body which ordered the investigation exceeded its authority and that the probe is being politically manipulated to damage Palin before election day.
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.
For the defense, Attorney Peter Maassen said the legislature has the authority to investigate the governor as it sees fit.
"If the legislature doesn't have the ability to oversee the actions of the executive, then who does?" Maassen said. "Is there anybody in this courtroom who really wants to live in a state in which the executive is only accountable to the executive?"
Maassen represents the Legislative Council, 10 Republicans and four Democrats who authorized the investigation, and others involved in the probe.
At first, Palin agreed to cooperate, but since being picked Aug. 29 to be Sen. John McCain's running mate, she, her family and staff have instead said the legislative investigation has been compromised by politics and they would only cooperate with a separate investigation run by the Alaska State Personnel Board, whose members Palin can fire.