WASHINGTON -- President Barack Obama's choice for a federal appeals court judge came in for rough questioning Wednesday by a Democratic senator over the judge's former affiliation with an advocacy group. 

At a Senate Judiciary Committee hearing on the nomination of Judge Andre Davis, a U.S. district judge in Baltimore, Sen. Russ Feingold, D-Wis., pointedly read from a 2005 private opinion sent to the judge by the federal judiciary's Codes of Conduct Committee. Obama has nominated Davis to serve on the Virginia-based 4th U.S. Circuit Court of Appeals. 

The conduct committee told Davis that his service as a board member of the Montana-based Foundation for Research on Economics and the Environment, or FREE, violated judicial conduct codes, and Davis quickly quit the board. 

But Feingold, long a stickler for judicial ethics, asked Davis about his initial contention, in a 2005 letter to the conduct committee, that there was no difference between his participation in the group's seminars and his decision to join the board. 

"It seems pretty clear to me that joining the board of an organization like FREE is actually a much more significant indication of your involvement with the organization and poses, in my mind, very different ethical questions," Feingold said. He asked Davis if he still didn't see the distinction. 

"I absolutely see the difference now, Senator," Davis replied. "I did not see it back in spring of 2004, when I was invited and agreed to join the board." 

Davis was one of three judges who left the foundation's board in the spring of 2005. At the hearing, Feingold read from the private opinion to Davis, which was also provided on request to The Associated Press. 

Davis' service on the FREE board, wrote the conduct committee, means "there is no practical way for you to disassociate yourself from the policies advanced by FREE, and your affiliation would reasonably be seen as personal advocacy of FREE's policy positions." 

The letter, signed by committee chairman Gordon J. Quist, also said that the affiliation "could create in reasonable and informed minds a perception that your impartiality may be impaired as to certain issues likely to arise in federal court." 

Feingold asked Davis why he didn't take any action about other judges who are still on the FREE board. Chief Judge Danny Boggs of the 6th U.S. Circuit Court of Appeals and Judge Edith Clement of the 5th U.S. Circuit Court of Appeals are currently on the FREE board, according to the group. 

Davis said that he took care of his own issues, "and I thought that that was the extent to which I had an obligation to proceed." 

The Community Rights Counsel, a liberal-leaning public interest law firm, filed ethics violations charges against several judges for their participation with FREE, including Davis and Boggs. 

Judge James Loken of the 8th U.S. Circuit Court of Appeals dismissed the complaint against Boggs in May 2005, finding nothing to substantiate CRC's charges that the judge's service on FREE's board created an appearance of impropriety. 

FREE, based in Bozeman, Mont., describes its orientation as "pro-market," adding, "We are intellectual entrepreneurs, explaining how economic incentives, secure property rights, the rule of law, and responsible prosperity can foster a healthy environment." According to the group, more than 80 percent of its funding comes from foundation supporters; it also receives funds from corporations, but says it uses no corporate money for its federal judges conferences, usually held at hotels and ranches. 

If confirmed by the Senate, Davis would join the 4th Circuit, which has jurisdiction in Virginia, West Virginia, Maryland and the Carolinas.