New York City’s Domain Awareness System is a vast surveillance network that continually records the movements and activities of city residents through thousands of cameras and other data sources—and makes this information available to police officers on their phones and workstations. Whenever a particular person or location comes under suspicion, officers can access this information retrospectively with the push of a button. A group of New York City residents challenged the City’s use of the System in the United States District Court for the Southern District of New York, arguing that this pervasive surveillance violates the First and Fourth Amendments.

In July 2026, the Constitutional Accountability Center filed an amicus brief supporting the plaintiffs. The brief explains that the NYPD’s warrantless use of the Domain Awareness System is inconsistent with the Fourth Amendment’s text and history, as well as with Supreme Court precedent recognizing that constitutional protections must keep pace with advances in surveillance technology.

As we explain, the Fourth Amendment is meant to preserve the same degree of privacy against government intrusion that existed at the Founding, protecting Americans from the dangers of a police state. The Supreme Court has repeatedly recognized that new digital technologies cannot be used to erode those longstanding protections. Unlike traditional investigative methods—like devoting a team of officers to tail a particular suspect—the Domain Awareness System enables law enforcement to collect, store, and analyze enormous amounts of information about people’s daily lives, creating detailed records that can be mined long after they are collected, even when the individuals involved are not suspected of wrongdoing. For practical reasons, NYPD officers cannot follow around every New Yorker throughout the day, recording where they go and what they do, yet the Domain Awareness System effectively makes that level of surveillance possible.

Because technologies that enable the government to monitor an entire population pose unique threats to privacy and liberty, they warrant especially careful scrutiny under the Fourth Amendment. The constitutional guarantee that people shall be secure against unreasonable searches protects not only individuals but also the public’s collective freedom from pervasive government surveillance and its chilling effects.

Our brief also discusses why the plaintiffs in this case have standing to challenge the Domain Awareness System. Seeking dismissal of the case, the City denies that the plaintiffs’ privacy rights have been injured. And in doing so, the City argues that automatically collecting and storing information about the plaintiffs’ movements and activities, 24 hours a day, is no different from, say, a police officer photographing someone in public. But that analogy ignores the very features that make the System so powerful: its ability to aggregate information from countless sources into a single, searchable surveillance network. The City also contends that the plaintiffs assumed the risk of surveillance by appearing in public, that collecting only portions of their movements does not violate their rights, and that no constitutional injury occurs unless a police officer actually searches for them in the System. But each of these arguments has already been rejected by existing Fourth Amendment precedent.

The Framers of the Fourth Amendment could not have imagined a technology like the Domain Awareness System, but they understood the fundamental importance of protecting people from unreasonable government intrusions into their private lives. By placing an entire city under continuous, warrantless surveillance, the Domain Awareness System threatens those constitutional protections and violates the plaintiffs’ Fourth Amendment rights.