During the exploration of the NSA’s assorted mass surveillance of the American public, it was revealed that they were collecting Americans’ emails in bulk on American soil, but cancelled the program in December of 2011. A New York Times investigation revealed this program stopped in name only.
The bulk collection of data on US soil, nominally focused on foreign nationals, was a program authorized by the secretive FISA courts, and subsequently was under their oversight. A separate, parallel program was collecting bulk emails overseas, which didn’t require any court approval or oversight.
Since the distributed nature of the Internet means even much internal US traffic goes overseas at some point, the NSA eventually decided that the bulk data they were collecting abroad covered basically everything they were getting with the US program anyhow, and with the two programs overlapping heavily, they chose to end the one with court oversight.
NSA programs came under scrutiny in 2013 following leaks by Edward Snowden showing how broad the surveillance had become. This led to considerable debate, but only very token reforms, and even those are now under fire in the wake of the Paris terror attacks, with many politicians seeing the mostly do-nothing “reforms” as a threat to national security.