In a letter to Vitter, the panel dismissed a 2007 complaint made by the left-leaning watchdog group Citizens for Responsibility and Ethics in Washington (CREW) because it said the matter allegedly occurred before his time in office, he was not charged criminally and his conduct did not involve use of his public office. As a result, the committee said it would not further exercise its jurisdiction over the incident.

“The Committee also wishes to make clear that this decision to dismiss this matter without prejudice should not be taken as a personal approbation or acceptance by any of the Members of the Committee of the kind of conduct alleged in this matter,” the letter stated. “In fact if proven to be true, the Members of the Committee would find the alleged conduct of solicitation of prostitution reprehensible.”

Vitter came under fire last year when his name surfaced in an investigation of a call-girl ring run by Deborah Jeane Palfrey, the so-called D.C. Madam. Palfrey was found guilty on April 15 on all accounts, including racketeering, money laundering and conspiracy.  She committed suicide last week.

Vitter, a staunch conservative, was never called to testify in the court proceedings, and he has never confirmed that he actually solicited prostitution. His office did not immediately return a request for comment.

But in a July 2007 press conference, he said he was engaged in a “very serious sin in my past for which I am, of course, completely responsible.”

CREW criticized the decision.

“The Senate Ethics Committee has once again done what it does best: nothing,” said Naomi Seligman Steiner, deputy director and communications director of the group.