The police use of Taser is limited to trained officers in accordance with Association of Chief Police Officers (ACPO) guidance. That guidance is clear that Taser use is currently restricted to authorised firearms officers (AFOs) where a firearms authority has been granted in accordance with criteria laid down in the ACPO Manual of Guidance on Police Use of Firearms. In addition AFOs are able to deploy Taser in operations or incidents where the use of firearms is not authorised, but where they are facing violence or threats of violence of such severity that they would need to use force to protect the public, themselves or the subject. A trial of the deployment of Taser in 10 police forces to specially trained police units not composed of firearms officers, for use when facing similar threats of violence, is currently being evaluated. The use of Taser in the trial is subject to the authority level of the appropriate authorising officer, thus placing it at the same authority level as for a firearms incident.