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."