In 2007, Mr. Ashmawy won national attention when he defended a young airman, Cassandra Hernandez, who said she was gang-raped at a party but was herself charged with committing indecent acts with the men she said had attacked her. Those charges were dropped.

Mr. Ashmawy will be working for the ethics office’s original board, although the two top board members have switched jobs. The board, largely made up of former members of Congress, is appointed by the House speaker and the minority leader. Porter J. Goss, a Republican who represented Florida in the House and is a former director of the Central Intelligence Agency, will take over as chairman. The co-chairman will be another former congressman, David E. Skaggs, a Democrat from Colorado. Mr. Skaggs served as the board’s chairman for the past two years under the Democratic majority.

The office has repeatedly clashed with the House Committee on Standards and Official Conduct, commonly known as the ethics committee. The office looks into cases against members of Congress and refers them to the ethics committee for further investigation. The committee has been accused of being soft on members of Congress, while some lawmakers have complained that the ethics office has been overly aggressive and inconsistent in deciding which allegations to pursue and which to ignore.

No one has been more critical of the ethics office than the Congressional Black Caucus. At least eight black lawmakers have been the focus of its investigations, most prominently Representatives Charles B. Rangel of New York and Maxine Waters of California, both Democrats.

One member of the black caucus, Representative Marcia L. Fudge, Democrat of Ohio, introduced a bill that critics said would have crippled the office. The legislation, which died when the previous Congressional session ended, would have prevented the ethics committee from issuing public statements in cases in which the ethics office had recommended that a complaint be dismissed. The existing rule gives the ethics committee discretion to release information in such situations.

The measure also would have prevented the ethics office from looking into any matter except on the basis of “a sworn complaint from a citizen asserting personal knowledge of any alleged violation.” Currently, a preliminary review can be started if two board members, one from each party, ask for it.

Representative Emanuel Cleaver II, a Democrat from Missouri who is the new chairman of the black caucus, said it continued to have issues with the ethics office.