In fact, there are many instances where no warrent is necessary - a police officer sees a gun in your car, etc. In those case, the search considered 'reasonable' and no warrant is needed.
The only question, then, is if the wiretaps in question fall among those instances.
Given the particulars and cirumstances, I'd say yes.
Sure there's a possibility -- but then, that's always a possibility in anything the government does, and so the full absence of such a possibility isnt a requirement.But categorically. Are you stating then that there is absolutely no possibility for abuse of such a system?
If it -is- abused, it will be taken care of in court.