A common criticism heard in recent years of federal law enforcement activities on the Texas-Mexico border involves the assertion that the border area, and a significant area extending inland, is a “Constitution-free zone.” While this phrasing involves quite a bit of hyperbole, federal law gives federal immigration authorities jurisdiction over an area extending up to 100 miles into U.S. territory. When at or near the border, the “border search exception” to the Fourth Amendment’s search warrant requirement allows certain types of warrantless searches and seizures. As Customs and Border Protection (CBP) and the Border Patrol conduct more enforcement activities, the extent to which the border search exception applies to activities further inside this 100-mile zone has come into question in Texas drug crime and other criminal cases.Under the border search exception, law enforcement officials may conduct limited searches and seizures, without a warrant or probable cause, at border crossings, airports, seaports, and checkpoints set up near the border like the Sierra Blanca checkpoint in West Texas. The exception derives from the right of a country to exercise control over its borders, but courts have generally held that the exception only allows brief questioning about immigration status or citizenship and matters relating to customs enforcement. Any additional search or seizure requires a reasonable suspicion of unlawful activity. See Almeida-Sanchez v. United States, 413 U.S. 266 (1973).
The 100-mile zone in which immigration officials may operate is based on authority granted by the Immigration and Nationality Act (INA). It allows warrantless searches of vehicles “within a reasonable distance from any external boundary of the United States.” 8 U.S.C. § 1357(a)(3). “External boundaries” include the entire U.S.-Mexico and U.S.-Canada land borders, as well as all coastlines extending 12 nautical miles out to sea. 8 C.F.R. § 287.1(a)(1). “Reasonable distance” is defined as 100 air miles inland from an external boundary, although certain customs or immigration officials have discretion to increase or reduce this distance. Id. at §§ 287.1(a)(2), (b).
Law enforcement officials conducting searches at border crossings, checkpoints, seaports, and airports routinely expand the scope of their inquiries beyond basic immigration-related questions. Most border stops that receive attention from the news media involve drug-related seizures and arrests. The justification for this is based in part on the enforcement of customs laws, and also on limiting searches to situations in which basic questions about immigration and citizenship lead to a “reasonable suspicion” of other unlawful activity.