The handheld units are now universally laser, but there are a couple places where radar is still the norm. Some cops have car-mounted radar units so they don't need to get out of, or open the window of the car. These are great if you want to watch a highway that doesn't get much traffic or to catch speeders while your own car is moving. Both scenarios are very common in rural areas.

Also, automated speed detection systems (aka "photo radar") use radar because you don't have to aim it like you do a laser.