The Senate Ethics Committee’s unanimous decision to release its report on the actions of former Sen. John Ensign (R-Nev.) on Thursday and refer his case to both the Justice Department and the Federal Election Commission marked its most stern rebuke of a colleague in recent history.

The leaders of the committee indicated that by releasing the results of the inquiry even after Ensign’s May 3 resignation, they were offering a warning to other lawmakers about the consequences of misbehavior, with Chairman Barbara Boxer (D-Calif.) and Vice Chairman Johnny Isakson (R-Ga.) detailing the report’s findings in speeches on the Senate floor.

“It is the hope of the chairman and myself and each member of the committee that every member recognizes the Senate Ethics Committee wants to be a source of information, advice and counsel to see to it this institution always rises to the occasion as the most ethical body in our government,” Isakson said. “But we will, as a committee, if it becomes necessary … pursue our responsibility as a committee and we’ll do what is required of us in this body.”

The sheer length of the 75-page report is remarkable, given that it surpasses past reprimands of Senators by more than 70 pages. When the Ethics Committee conducted an inquiry into communication between former Sen. Roland Burris (D-Ill.) and former Illinois Gov. Rod Blagojevich (D) and found that the Senator had acted improperly — but not illegally — the committee issued a three-page “letter of qualified admonition.” When former Sen. Larry Craig (R-Idaho) was arrested for lewd conduct in an airport restroom and pleaded guilty to disorderly conduct, the committee issued a more serious “letter of admonition” of similar length.

The depth of the Ensign report appears to “an indication of the seriousness of this particular case and how long it has dragged on and their strong desire to finish it,” said Lisa Gilbert of the nonprofit consumer group Public Citizen.

The special counsel concluded that Ensign likely violated both federal civil and criminal laws as well as Senate rules in his pursuit of an extramarital affair with the wife of an ex-aide and the subsequent cover-up. Boxer said on the floor that the findings were “so disturbing” that had Ensign not resigned, the allegations against him were “substantial enough to warrant the consideration of expulsion.”

Since 1789, the Senate has expelled only 15 of its Members, all but one of whom were charged with supporting the Confederacy during the Civil War, according to the Senate historian’s office. The fifteenth was William Blount (Tenn.), who was charged with treason in 1797.

“It is rare — and I can tell you personally, it’s a situation I hope I’m never involved in again, but as I’ve said, it’s an essential process to the integrity of this body,” Isakson said of the inquiry.

Most complaints of rules violations never reach the stage of a public rebuke. In 2010, the Senate Ethics Committee received 84 complaints of rules violations, began or continued a preliminary inquiry in 12 cases and then dismissed eight of those for lacking merit. In 2009, the committee received 99 notices of alleged Senate rules violations and conducted a preliminary inquiry in 13 cases, eight of which were dismissed. The committee issued one letter of admonition that year, in the matter of Burris.

Though Ensign’s case was a departure from previous enforcement tactics, experts say it could have more to do with the severity of the allegations than a shift in policy.

“It’s easy when a guy has left for them to look tough on the ethics — you’re not doing it with a sitting Senator, you’re not disrupting the body,” said attorney Stephen M. Ryan of McDermott Will & Emery.