Under attack from Democrats for tolerating a “culture of corruption,” House Republican leaders are following Democrats in forcing Members to step down from key committee posts when a federal criminal investigation culminates in an FBI raid.

But the forced resignations of Rep. John Doolittle (R-Calif.) from the House Appropriations Committee and Rep. Rick Renzi (R-Ariz.) from the Intelligence Committee raise a question for both parties: Shouldn’t there be a formal standard for such departures?

House rules provide only that when a Member is convicted of a crime carrying a sentence of more than two years, he or she “should not” engage in committee business or vote on the floor. Further action is up to the Committee on Standards of Official Conduct and the House membership.

Both parties have formal rules that a leader or committee chairman who’s indicted automatically steps down from those posts, but there is no formal rule applying to rank-and-file Members.

Republican leaders found themselves in no end of political trouble in the 109th Congress when they moved to alter the step-down rule to protect then-Majority Leader Tom DeLay (Texas) before he was indicted by a Texas grand jury, only to face a rank-and-file revolt. After balking at first, leaders forced former Rep. Bob Ney (R-Ohio) from the chairmanship of the House Administration Committee months before he pleaded guilty to bribery charges. Then-Rep. Duke Cunningham (R-Calif.) remained a member of the Appropriations panel until the moment he pleaded guilty to bribery.

Last year, then-Minority Leader Nancy Pelosi (D-Calif.) forced Rep. William Jefferson (D-La.) off the House Ways and Means Committee four days after the FBI raided his office in the Rayburn House Office Building. Jefferson has since been given a seat on the Small Business Committee and — astoundingly, in our view — Pelosi has considered appointing him to the Homeland Security Committee despite the ongoing bribery investigation.

In November, after Republicans lost control of the House partly because of the corruption issue, then-Majority Leader John Boehner (R-Ohio) announced that henceforward “clear likelihood of serious transgressions will lead to suspension from important committee positions. Guilt will lead to immediate and severe consequences.” That’s certainly a stiffer stance, but it’s still flexible.

Doolittle and Renzi stepped down from Appropriations and Intelligence knowing they’d be forced off following raids this month. Doolittle has no other committee assignment, but Renzi was permitted — at least temporarily — to retain his seats on the Natural Resources Committee and the Financial Services Committee.

Meanwhile, other Members under investigation have not been required to depart from any committee posts, most notably Appropriations ranking member Jerry Lewis (R-Calif.), who has spent roughly $900,000 on legal bills since the federal probe of him began.

Other Members reportedly under investigation who remain in place on their committees include Reps. Gary Miller (R-Calif.), Ken Calvert (R-Calif.) and Alan Mollohan (D-W.Va.), who stepped down from the House ethics committee in the previous Congress but not from Appropriations.

Obviously, an FBI raid is not the only potential sign that — as Boehner put it — the “clear likelihood of a serious transgression” exists. But right now, for both parties, there is no real standard. It’s evidently “we’ll know it when we see it.” That’s not good enough.