Edward Snowden’s leak is really about intelligence sharing within the Anglosphere known as Five Eyes or FVEY.
FVEY is governed by a 1946 agreement, UKUSA, to share (signals) intelligence between United Kingdom, United States, Canada, Australia and New Zealand. The purpose of the surveillance is to preempt and quash both internal and external dissent against the post-World War II, post-Cold War Anglo-Saxon world order to safeguard the Anglo-Saxon model of the economy and the way of life, in particular after 9/11.
The American legal framework which legitimizes the National Security Agency (NSA) consists of UKUSA, ABCA Armies program of 1947 for cooperation among the armies of UKUSA countries, Foreign Intelligence Surveillance Act of 1978 Amendments Act of 2008 which added Title VII (in particular Section 702), and PATRIOT Act of 2001, Title II, Section 215.
At issue is the constitutionality of the scale and scope of NSA surveillance, under the cover of the legal framework, which is for the United States Supreme Court to determine.