NHTSA (U.S. National Highway Traffic Safety Administration) is seeking input into a just-released report on the effectiveness of LEDs as used in taillights. The agency noted in the Feb. 28 Federal Register that the report "does not support a firm conclusion about whether LED stop lamps and LED CHMSL are more effective than incandescent lamps." NHTSA relied on crash data, not actual physical testing, for the report. Some data indicate an improvement in safety—specifically, a 3.6% reduction in rear-impact crashes in vehicles using LEDs. Other data are less conclusive, including the fact that there was an increase in rear impacts for the majority of the 17 study vehicles that switched from incandescents to LEDs. A complicating factor is that all of the vehicles that switched to LEDs also underwent a rear-lighting reconfiguration or a vehicle redesign, making it difficult if not impossible to isolate the performance of the LEDs. Lab work done prior to issuance of this report "suggested that LED lamps were more beneficial than incandescent lamps at preventing rear-impact collisions." NHTSA will rely on the testing, the report, and public input to decide on possible future rulemaking. Comments are due June 28 at http://www.regulations.gov.