The Washington Post has an article saying that the Department of Justice's concerns over the newly broad interpretation of the "speech or debate" clause in the U.S. Constitution has led to the spiking of a number of investigations of Members of Congress, including one involving U.S. Rep. Don Young (R.-Alaska). Young was being probed for his role in the change of language in a bill passed by Congress that benefited a highway project in Florida backed by one of his campaign contributors. According to the article, that investigation was dropped along with others involving Members of Congress out of a fear of violating the constitutional provision shielding the work of legislators from interference from the executive branch.
Concerns over the "speech or debate" clause may also have contributed to federal prosecutors' decisions in the Ted Stevens trial to limit the evidence the government introduced regarding the amount of legislative assistance the Senator had given Bill Allen and VECO, the multinational oil-services corporation he ran for decades. The Los Angeles Times, for example, alleged much juicier help regarding the Pakistani government's payment for a $70 million pipeline than anything the prosecution brought up as assistance for VECO in Congress provided by Ted Stevens.