The National Security Agency/Central Security Service (NSA/CSS) leads the U.S. Government in cryptology that encompasses both Signals Intelligence (SIGINT) and Information Assurance (IA) products and services, and enables Computer Network Operations (CNO) in order to gain a decision advantage for the Nation and our allies under all circumstances.
The PRISM program is the latest of many surveillance programs to come to light as problematic. As technology advances (as it has from snail mail to telegraph to radio to telephone...) there will be advances in surveillance and these will be met by probably undue trust by private citizens. Incidents of what have later been determined as unconstitutional breaches of privacy are not hard to find.
The other programs like MAINWAY, Fairview, STELLARWIND and others back to ECHELON have used computers to correlate information gathered by various means. Wullenweber antenna arrays are spread over the globe and information from Snowden has revealed that telecoms provide info directly to the government.
The growing technology that makes easier the task of correlation of metadata such as call records and some details of text/email content with other data possibly including visual surveillance (maybe involving the NRO) begs for oversight with published understandable standards.
Not to go deep into conspiracy land here but there is a history of government surveillance programs by agencies with black budgets that weren't even acknowledged as existing.
Are new laws clarifying the 4th Amendment needed?
If so, what restrictions are reasonable?