The Justice Department is probably correct in saying that it was legally entitled to search a congressman's office last month. But in ignoring history and established conventions in that case, some legal scholars say, the Bush administration has again unsettled widely shared understandings of constitutional relationships and freedoms that have existed for generations.

As with the administration's assertions that it may ignore a law on domestic eavesdropping, reinterpret other laws through presidential signing statements and prosecute journalists under espionage laws, specialists in constitutional law and history said, the Justice Department's justification for the search is an aggressive use of executive power.

In the search case, there is broad academic consensus that the constitutional protection for Congressional speech and debate does not extend to evidence of criminal conduct, even if it is in a Congressional office.