When is it appropriate for law enforcement to engage in wiretapping without first obtaining a search warrant?

it is never legal to engage in wiretapping

when the wiretap is connected to a telephone used by a previously convicted foreign intelligence officer

o when the wiretap is part of an investigation into possible terrorism or espionage in which probable cause has been determined

when the wiretap is part of a blanket tap of all of the telephones in a specific neighborhood or community