The problem is the attitude that the NSL is just another "tool" in the FBI's toolbox, to be used as aggressively as can be in the pursuit of criminals. There is no effective check or balance against this -- we are forced to rely on the investigators to use their discretion, knowing that any challenge to such a warrantless request has about a zero % chance of being successful before the FISA court.<p>I would like to see an activist attempt to challenge such an order, or even refuse to cooperate in an NSL where the FBI is acting outside of its legislative and Constitutional authority. However, the overwhelming incentive in any such situation is to cooperate. And from what I have read, even if the FBI is acting illegally, the subject of the investigation aided by the NSL may still be a fairly loathsome criminal -- so, you have to be quite a principled activist to risk prison time to make a civil rights statement, when this is directly going to benefit a badguy in the specific instance.