Cellular Dragnet: Active Cell Site Simulators and the Fourth Amendment

Abstract

This Paper examines government use of active cell site simulators (ACSSs) and concludes that ACSS operations constitute a Fourth Amendment search. An ACSS — known colloquially as a stingray, triggerfish, or dirtbox — mimics a cell phone tower, forcing nearby cell phones to register with the device and divulge identifying and location information. Law enforcement officials regularly use ACSSs to identify and locate individuals, often with extreme precision, while sweeping up the identifying and location information of hundreds or thousands of third parties in the process. Despite the pervasive use of ACSSs at federal, state, and local levels, law enforcement duplicity concerning ACSS operations has prevented courts from closely examining their constitutionality.

ACSS operations constitute a Fourth Amendment search under both the trespass paradigm and the privacy paradigm. Within the former, an ACSS emits radio signals that trespass on private “effects.” Under the Jones reinvigoration of the trespass paradigm, radio signals “touch” cell phones for the purpose of obtaining information, constituting a “Fourth Amendment trespass.” Radio signals also trespass under common law property and tort regimes, and the Paper proposes a new rule, consistent with existing trespass jurisprudence, to target only those radio signals that intentionally and without consent cause an active physical change in the cell phone. Within the latter, ACSS operations constitute a Fourth Amendment search because they violate users’ subjective expectations of privacy that society can and should recognize as reasonable, particularly if Fourth Amendment jurisprudence continues to eliminate secrecy as a proxy for privacy. Until courts decisively recognize warrantless ACSS operations as illegal, however, advocates and litigants can implement several interim remedial measures.

An ACSS is an undeniably valuable law enforcement tool. Subjecting ACSS operations to Fourth Amendment strictures will not hinder their utility but rather ensure that this powerfully invasive technology is not abused.

Keywords: Fourth Amendment, stingray, cell site simulator, constitutional law, privacy, trespass

JEL Classification: K11, K14, K30