Ars Technica looked through some documents detailing government expenditures and found that the US Marshals have spent over $52,000 on the radars since 2012. As each Range-R costs $6,000, the agency must have at least eight units in its possession. Even so, law enforcement agencies have managed to keep the fact that they've been buying Range-Rs on the down low for years, until an appellate court (for the first time) referenced its use during an arrest made by the US Marshals last month.

See, in 2001 the Supreme Court ruled that authorities cannot use thermal cameras or any radar system that was only being developed at the time to scan someone's house without a warrant. But the authorities in last month's incident used the Range-R without the proper paperwork, prompting the judges to note that usage of the device "will soon generate many questions for [the] court." Sure enough, privacy advocates are now concerned that Range-Rs are being used regularly without warrants. As Hanni Fakhoury, a lawyer for the Electronic Frontier Foundation, told USA Today: "The problem isn't that the police have this [radar]. The issue isn't the technology; the issue is always about how you use it and what the safeguards are."

[Image credit: L3 CyTerra]