Police are to continue using 'Taser' stun guns after a 12-month trial was successful, they say.
The guns have not yet been used on suspects in the Thames Valley
The guns have not been fired in anger since the trial started in the Thames Valley, but have acted as a deterrent, a police spokesman said.
The guns are designed to disable a suspect with an electric shock instead of using traditional firearms.
But some campaigners, including Amnesty International, say the guns should not become standard police issue.
Amnesty claim the weapons have not been independently tested and should be treated as a "lethal weapon".
The taser, which has been in use in the USA for over 20 years, fires two darts into the suspect using compressed air.
When the darts hit, this completes an electric circuit and a five-second 50,000-volt charge is released down the cable, causing the suspect's muscles to contract uncontrollably.