The House Ethics Committee agreed Wednesday to take the unusual step of hiring an outside counsel to investigate its own actions before moving ahead again with the long-stalled inquiry into allegations of wrongdoing by Representative Maxine Waters, a Democrat from California.

Billy Martin, a former Justice Department prosecutor who now works for a Washington law firm, was named as the special counsel. He was asked to first determine if Ethics Committee staff members violated House rules last year during the investigation of Ms. Waters by passing information inappropriately to certain Republican committee members and making statements that showed a bias against Ms. Waters.

“Serious allegations have been made about the committee’s own conduct,” an Ethics Committee statement said. “The committee has not taken these allegations lightly.”

Only after Mr. Martin completes this review will the committee decide if it will continue to investigate Ms. Waters, who has asked that the case against her be dismissed, based on the missteps by committee staff members that she argues makes it impossible for her to get a fair hearing. If a further inquiry is approved, Mr. Martin will then look into the allegations against Ms. Waters, a process that could take months, before the Ethics Committee decides whether to take any action against her.

In a statement, Ms. Waters said she was “confident that the counsel’s review of the committee’s misconduct will conclude that my rights were violated and further investigation of me is not warranted.” She called for the findings to be made public.

Ms. Waters was charged last August with violating ethics rules in actions that related to a Boston-based bank, OneUnited, which her husband owned stock in, as it sought federal bailout funds in 2008. She denied wrongdoing, saying she was generally trying to help out minority-owned banks.

The charges were suspended and the matter referred back to the Ethics Committee late last year after the committee’s staff asserted that Ms. Waters or others had withheld evidence. In fact, it now appears that the staff had failed to request critical evidence before it brought the charges, including copies of e-mails from Ms. Waters’ chief of staff, according to a memo written late last year by the former Ethics Committee staff director — a document that became public only this week.

Mr. Martin, a partner at Dorsey & Whitney, served as a local prosecutor in Ohio and at the Justice Department, including supervising political and organized crime grand jury investigations.