The Chicago Tribune reports that judges in Cook County, Illinois, have been dismissing speeding tickets issued to drivers whose speed was measured with laser guns rather than boring old radar. The traffic court has taken the position that evidence gathered by means of laser-gun technology (or "lidar") fails the Frye test because it has not yet been proven in an Illinois court to be scientifically reliable, and so it is not admissible.
Lasers do work in general, of course — I personally own several, and only one of them is attached to the head of my pet shark. The rest are in CD and DVD players and other electronic equipment, and I assume there is one in the magic kitchen box that heats up my food. Lidar itself is used in many other ways in addition to giving you a ticket — it has been used to measure the distance to the Moon (always useful), and this robot uses it, probably to hunt and kill children. According to the Tribune, the laser-gun-speed-detect-o-ray has been tested and found reliable by some courts outside Illinois, but Cook County judges understandably want it tested there too.
It could of course be tested in a Frye hearing there in Cook County, but such a hearing has not yet been held, because, you see, they are hard and require evidence. "The legal procedure required to prove a technology is scientifically reliable . . . is laborious and expensive," the Tribune said experts had told it. "The hearing requires witnesses and can stretch for days." A spokesperson for the county law department said this was why lidar had not yet been tested in Chicago courts, where holding "hearings" that require "witnesses" is apparently a rare occurrence. The spokesperson said that recently the department had begun asking for Frye hearings in cases where a driver has an attorney, but that so far every such defendant has (unsurprisingly) chosen to pay the fine rather than try his luck against someone armed with a laser gun. She said they were hoping that the state attorney's office would seek such a hearing in a more serious case where a defendant has more to lose.
She also said that if all else failed, prosecutors would (in the Tribune's words) "seek a state law that explicitly recognizes lidar as scientifically reliable." See, that's not really how science works, as the state next door demonstrated back when it considered redefining the value of π. Pi is what it is, even if you did get a state law sayin' it ain't, and the same principle applies here. In this case, of course, lidar probably is reliable. It doesn't seem too much to ask that the State prove it, though.