The police look at the circumstances (level of injury (physical or mental), financial loss etc, etc) and take a measured view – considering whether the suspect is a serious and repeat offender, their age, admissions made and if remorse is displayed, the victims wishes and the impact the crime has had on them, along with a raft of other factors. A Home Office ‘Gravity Matrix’ is used to assist this process. Cautions have an important role to play in proportionate criminal justice outcomes, which the police dispense correctly most of the time – it can be tricky.
Personally, I feel the use of cautions should be reviewed – to improve consistency across UK Forces and to ensure the public mood for certain crimes are properly gauged. The CPS have a role to play in this. They need to increase their appetite for prosecuting offences by demonstrating a little more courage in taking allegations (which aren’t necessarily ‘sure fire winners’) forward to court and trusting bench’s / juries to reach sensible verdicts, whilst allowing victims their day in court.
OP – Yes, we have done this – http://singletrackworld.com/forum/topic/road-rage-video