Here's what the weapons are, how and when they're used, and why they're controversial.

"Less lethal" weapon shoots a microwave beam, causes painful hot spots. Scientists worry targets could suffer permanent damage. Photos: Researchers cook up microwave weapon Scientists are questioning ...

As with anything else requiring equipment, both in law enforcement and any other field, evolution occurs. Changes in engineering, the creation of new materials, studies of past events, successes, ...

The Maryland National Guard is set to establish a crowd control reaction force by April, following an order from a top military commander requiring every state, territory and the District of Columbia ...