[Cboldt]

Listening into someone from one of the drug cartels calling a major dealer in the US without a warrant would IMO be unreasonable.

That was one of the primary uses of warrantless wiretapping in the '70's.

What if the drug kingpin was also considering terror? There is one instance of a drug kingpin downing an airplane in order to dispose of witnesses. IIRC, over 100 dead.

Here are some facts on that one (granted, the terrorism was not "in the US," but the incident points out that there is no way to untangle "terrorism" from other activities.

Incidents of Major Airline Terrorism. By Wm. Robert Johnston.

Nov. 27, 1989 -- A bomb exploded aboard a Colombian Avianca Boeing 727 passenger jet departing Bogota, Columbia, en route to Cali, at 7:16. Exploding 5 minutes after takeoff in a passenger seat, the bomb ignited fuel vapors and caused the plane to crash, killing all 107 aboard as well as 3 on the ground. The bomb was planted by members of the Medellin drug cartel, led by Pablo Escobar who was charged by the U.S. in August 1992. The bomb may have been supplied by Islamic terrorists, based on similarities to the one that destroyed Pam American Flight 103. Five passengers were informants who had been targeted by the drug cartel. Two Americans were among those killed. Fatalities: 110.

[airedale]

If you just found out about it and knew that the terror attack was going to occur quickly the 72 hour rule would apply. The difference is that you know who the kingpin is since they don't take the same steps to cover their tracks that Al Quada does. Your not looking for sleeper cells and known Al Quada members trying to contact them or being contacted by them. Arranging for the wire tap in this case would be a more routine tap.

If you knew the kingpin had ordered the attack and found out a phone line from one team in the plot to another by means of echelon the exigent circumstances to prevent the attack would probably make the listening and using the info reasonable. If they were just going to hit an individual rather than taking out a commercial plane to do it then it gets murkier IMO.