Thermal imaging registers the heat of all objects. It uses a detector that is sensitive to infrared radiation, which exists in all objects. Uses for thermal imaging in law enforcement include: (1) nighttime patrol; (2) general surveillance; (3) crime scene investigation; (4) perimeter surveillance; and (5) officer safety. However, this technology is not cheap. Handheld or car-mounted systems retail for $10,000 to $12,000, while a helicopter system runs close to $200,000. In addition, the U.S. Supreme Court has ruled that scanning a home with an infrared camera without a search warrant constitutes an unreasonable search barred by the Fourth Amendment. Police around the country have been instructed not to use thermal imaging until the final step of an investigation. At that point a properly orchestrated investigation will have established enough probable cause to obtain a search warrant to use the thermal imager. The article concludes that, as prices come down to where police departments can afford it, and rights issues clear up in the courts, the thermal imager may soon be a commonplace tool of law enforcement.