There are no legal standings against owning one. A procecutor might make it look evil in a court of law in the event of a self-defense situation, but I find the use of a laser can be easily justified as the last line of deterrence before the trigger is pulled and as a simple aiming device for a high-stress situation where a properly aimed shot was not possible under the given conditions.
Medical, industrial, and entertainment lasers are regulated by the FDA but most of them are class IV lasers capable of causing physical harm upon exposure to skin.
I'm sure most states consider it a misdemeanor to aim it at law enforcement and I think a felony to shine one on an airplane. There used to be a large stink about laser pointers at public schools but it seems to have faded away. In general, it seems like a lot of people frown upon them and Hollywood certainly cheapened it's image.
