Why would you assume that "collaboration" is lawful? Just because 2 parties agree to do something illegal or unconstitutional through "collaboration" doesn't make it legal.
Domestic spying on citizens that are not suspected of wrongdoing is illegal and unconstitutional. If the government suspects illegal activity, they are required to go to a court and have a judge issue a warrant to allow them to search and/or seize evidence. Of course, they have been revealed to NOT be doing that, basically acknowledging that the Constitution has, for all practical purposes, been dismantled and discarded. And most people seem to be okay with that. <sigh>