Failure to respond to the request will often lead to a summons to court for both offences, although a successful prosecution for the underlying offence is fairly unlikely as the prosecution will usually be unable to prove who was driving. Additionally, the penalty for failure to provide information is higher than most standard traffic offences, partly as a deterrent and partly to avoid refusing to identify the driver from being the "better" option in all but the worst of circumstances.

There was a loophole for a while whereby you could return the form, correctly filled in but not signed, meaning that you have provided the information, but it is not admissible as evidence in court. This is currently still effective in Scotland. In England, case law has been established such that the form is not valid unless signed, and would usually result in the police placing the defendant firmly in the "smartass" pile and proceeding with a prosecution for failing to provide information. Just lately, police have been increasingly taking the more pragmatic approach of calling the motorists bluff in cases where he nominates himself and the case can be dealt with by way of a training course or a simple fixed penalty. They will often now offer the course or the penalty, and still charge for both offences if the driver elects for the case to progress to court.