Key aspects of this surveillance include:

Collection of Communications Data: Intelligence agencies like the National Security Agency (NSA) have collected vast quantities of data, including phone call records (metadata), text messages, emails, and internet browsing information from millions of people. This is often done with the compelled assistance of major tech and telecommunications companies such as Google, Meta, AT&T, and Verizon.

Legal Authorities: Much of this surveillance is conducted under broad legal authorities like the Foreign Intelligence Surveillance Act (FISA) Section 702 and Executive Order 12333, which critics argue allow for the collection of data without individual warrants and with limited judicial oversight. The government often characterizes the collection of Americans' data as "incidental" when targeting foreign individuals abroad.

Physical Monitoring Technologies: In addition to digital surveillance, law enforcement at federal, state, and local levels use various technologies to monitor physical movements, including automated license plate readers (ALPRs), extensive networks of surveillance cameras (often with facial recognition capabilities), and location tracking via mobile phones.

Data from Private Brokers: The government also bypasses some constitutional protections by purchasing large amounts of personal data from commercial data brokers, including location information from mobile apps.

Targeting of Specific Groups: Reports indicate that surveillance efforts have disproportionately targeted activist groups (such as Black Lives Matter and immigrant rights organizations), journalists, and Muslim, Arab, and South Asian communities. 

Civil liberties advocates argue that these indiscriminate programs treat all citizens as potential suspects, infringe upon constitutional rights to privacy and free expression, and have led to an expansive domestic intelligence apparatus often referred to as a "surveillance state". Organizations such as the ACLU and the Electronic Frontier Foundation are involved in ongoing efforts and lawsuits to challenge and reform these mass surveillance practices.