Laser speed guns, sometimes called Lidar guns, have grown in popularity with law enforcement agencies as they have become more user friendly and lost some of their shortcomings. Their biggest advantage over radar is that the laser beam is typically not detectable, except as you are shot. Little late then.
There is much ado about how the laser can clock a single car in a group of cars and on congested roads. This is more propaganda than a real threat. Yes, the beam is narrow and it doesn't radomly bounce around like a radar signal, but there are practical limitations related to distance, passing vehicles, location of the laser operator, and the density of traffic that hinder getting honest reliable readings in many circumstances.
The best defense against laser is mounted above your nose. Your eyes will save the day. First, your eyes will pick up the flashing headlights of motorists coming from the other direction, a common courtesy that needs to be cultivated. Second, laser operators need more time to acquire a visual tracking of a vehicle and at the same time they cannot obtain a legitimate speed reading much beyond 1000 to 1200 feet. (Speed readings are possible at much longer distances, but a host of factors make these longer speed readings unreliable, especially in heavy traffic or bad weather.) Consequently, you should be able to see the laser operator before he can measure your vehicles speed.
In expressway situations the sighting of someone standing along side the road, facing your way, especially if he is adjacent to a car or motorcyle is cause for being on alert. One or more persons standing in one position on an overpass is yet another reason for caution. However, one tactic that is difficult to detect is a laser operator hidden from oncoming traffic who then shoots vehicles from behind as they move away. This latter set-up often involves chase cars parked on following entrance ramps. Hope for flashing headlights!
There will be the same tell-tale signs on other streets roads and highways. Laser operators will shoot through glass, so don't assume they will always have the window open. The patrol cars are often parked at an angle to the roadway. Unlike radar, laser units must be aimed and manually activated. This means an officer cannot be doing multiple tasks at one time. Talking on the cellphone or filling out reports are not compatible with laser operation. Also, laser is not used in a moving mode, a common tactic for radar operators, even if they are on their cell phones.