It's simple

There's a Drug to Terrorism link. So, the Feds are going to target drug traffickers with the whole NSA data slurping thing.

What impact would this have if they were being successful? A reduction in the supply of drugs. And how can we measure the supply of drugs? Prices. If the prices of street drugs is going up, then the Feds are being successful with the whole "balance between safety and government intrusion."

But, if the prices are going down and new products are being introduced, then we can say that the NSA and FBI and law enforcement are failing with the current strategies.

Look at historical street drug prices. They are not going up. There are new products being introduced. So, let's just call the whole wiretapping everyone thing a failure and shut down the NSA and the FISA court.