I don't understand the whole fight subpoenas and contact the customers thing. Isn't a big part of the PRISM system them NOT having direct access and just trying

I don't understand the whole fight subpoenas and contact the customers thing. Isn't a big part of the PRISM system them NOT having direct access and just trying to collect all the data from certain systems and rebuilding it, or pulling stuff from it? Like basically just tapping the line?