By my layman's point of view, we already have existing laws that are being flouted, among the the 4th Amendment which requires specific warrants for specific investigations, and the various laws authorizing and limiting surveillance. They do whatever they want despite these existing laws, by a) just doing it, and b) getting the administration through the Attorney General to reinterpret laws so that what was illegal is now justified by the very laws that previously made things illegal, and c) a captive, secret court that only hears one side of any query by the government and rubber stamps all NSA actions.

Given that, what good would a new law do? They already have everything in place to subvert any law they want, and their chief tool is mere will.

What might change things is public outrage and muscular congressional hearings, a la Watergate. I can't see that ever happening again.