What powers do police have to stop vehicles?
A common complaint we hear is that the police officer who arrested our client had no reason for stopping them in the first place. So, what powers do the police have to stop a car?
There are two sections of the Road Traffic Act 1988 that are relevant here. First, section 35 requires drivers to obey traffic directions, which includes a direction from a police officer engaged in the regulation of traffic on a road to stop. Conviction will result in a fine of up to £1,000 and three-penalty points. This sort of power is really intended to control traffic rather than to stop a vehicle so the driver can be spoken to by the police officer.
Section 163 grants police a much broader power to stop a vehicle being driven on a road. Unlike section 35, there is no requirement for the officer to be directing traffic; however, the officer must be in uniform. Failing to obey is a criminal offence with the same punishment as the section 35 offence.
There are a couple of caveats to the section 163 power. First, as has been said the officer must be in uniform. This means that an officer out of uniform cannot require a vehicle to stop even if he happens to be driving a marked police car. Secondly, the power applies only to vehicles on a road, which is a defined term within the meaning of the Road Traffic Act. This means that if you are not on a road the police officer has no power to stop you. Because of the way “road” is defined, places like car parks may not count as a road meaning any stop in such a place could be unlawful.
An important limitation to the police power to stop vehicles is that the officer must exercise the power for a proper purpose. In the case of R v Waterfield  3 All ER 659, the court held that section 163 does not permit the police to stop a vehicle for an improper purpose. This line of reasoning was followed a decade later in Hoffman v Thomas  RTR 182 in which the court held that a constable must be acting in execution of his duty for a stop under what is now section 163 to be lawful.
The issue in Hoffman was whether a police constable had power to require a motorist to stop and at a census point. The court in that case found that assisting in the conduct of a census was not part of the police officer’s duty, which at common law is to protect life and property and, as such, the constable was not acting in the execution of his duty and so the motorist was not guilty.
In some circumstances, police officers have been deployed to work with debt collectors looking for vehicles that have incurred parking fines. The police officers stop the cars identified by the debt collectors so that the debt collector can speak with the driver and seize the vehicle. But if the police only have powers to stop vehicles when acting in the exercise of their duty then what is their duty? The now defunct Association of Chief Police Officers described the police’s job as being “to prevent crime and disorder”. In Hoffman, the court said it was to protect life and property. It is difficult to see how police officers working with debt collectors are executing their duty as police officers and thus it is quite possible that such stops would be unlawful.
Are random checks unlawful? The answer to this comes from a line of cases beginning in 195 with Chief Constable of Gwent v Dash  R.T.R. 41 where the court held that a random stop of vehicles to see if drivers had been drinking was lawful. In the 1993 case of Normand v McKellar 1995 S.L.T. 798, the defendant was stopped as part of a routine enquiry. Upon stopping him, police officers noted that his vehicle was not displaying a tax disc and so he was reported for the offence. He successfully argued that the police officer’s evidence should be excluded at trial because the stop was unlawful. However, the Crown appealed successfully with the appeal court judge saying that,
“where an offence was patent to be seen because something was not being displayed which ought to have been displayed, there was nothing which could be described as an invasion of liberty or an excess of police powers.”
In 1999 the Scottish High Court heard the case of Stewart v Crowe 1999 S.L.T. in which they held that random stops conducted as part of a Christmas drink driving campaign were lawful. It’s worth noting that in Stewart police were tasked with stopping cars randomly but officers were only permitted to require a breath test if they suspected the driver had been drinking. Had their orders been to require a breath test from all drivers that would certainly have been unlawful. Mr Stewart’s problem was that after he was stopped, the police officer dealing with him smelled alcohol on his breath and so had a good reason to suspect he was drink driving.
In summary, the police do not need a specific reason for stopping a vehicle; however, they must be acting in the course of their duty and make the stop for a proper reason. The officer must be in uniform and the requirement to stop must be made on a road. Failure to comply with any of these requirements will render the stop unlawful. However, even where the stop is unlawful the courts are likely to admit evidence flowing from it unless the police officer’s actions were so oppressive that it would be unfair to admit the evidence.
If you have been accused of a motoring offence and need help then don't hesitate to contact one of our expert motoring solicitors.