In the US, more than two million people have been hit with Tasers by police over the past decade and more than 9,200 in the UK since they were widely introduced in 2009.
But a new study has raised concerns about the impact that the 50,000 volt shock these 'non-lethal' weapons inflict on the human body.
Researchers, who were funded by the US Department of Justice, found the burst of electricity from stun guns can impair a person's ability to remember and process information.
Some of those who were hit by the electric weapons also showed short-term declines in cognitive function which were comparable to mild dementia.
The scientists behind the study said it raises serious questions about the ability of suspects to understand their rights and answer questions after they have been hit by a Taser.