The Fourth Amendment of the U.S. Constitution prohibits unreasonable search and seizure and requires probable cause prior to the issuance of a warrant. Reassessments of the Fourth Amendment became especially important in the early 20th century as emerging technologies provided government officials new opportunities to monitor private behavior. In Kyllo versus United States, the Supreme Court ruled that the use of sensory-enhancing technology to see through traditional privacy barriers constituted an illegal search in violation of the Constitution’s Fourth Amendment protections. The Kyllo decision represents a narrowly defined respite from the ever-encroaching powers of government-sponsored surveillance. Kyllo argued that surveillance that relies on technology that is not in general public use represents a practical problem. The Kyllo decision was intended to address the problem of government intrusion no matter what the method of surveillance. The Kyllo standard for the application of sensory-enhancing technology has important implications for law enforcement and the ongoing fight against terrorism. By creating a new standard, the Court settles some constitutional questions and raises others. Law enforcement is challenged to stay within the bounds of established precedent without unnecessarily forgoing power that the Supreme Court would hold as legitimate. References