Are you really allowed to go 10% above the speed limit before you are fined?
What is the reality of the 10% rule when it comes to breaking the speed limit?
How many times have you heard people say that you won’t get fined if you’re only exceeding the speed limit by 10% or less? If you’re anything like me, you’ve probably heard it dozens of times. But what’s the truth? Do police really not issue fines unless you are going more than 10% above the speed limit (or even 10% plus 2mph)?
Under UK law, speeding is a strict liability offence. This means the police and Crown Prosecution Service do not need to prove that you meant to speed or even knew you were speeding. If your vehicle travels above the legal limit, the offence is complete. That’s it. It also means drivers have no legal right to a margin of error. So, essentially, if you are caught doing 31mph in a 30mph zone, you could theoretically be fined for speeding.
However, in reality, police forces do not apply the law that strictly. It depends on the force but, for example, London’s Metropolitan Police said in a response to a freedom of information request: “The Met observes the current National Police Chiefs’ Council [NPCC] guidelines which states that enforcement action should commence as soon as a speed is at +10% plus 2mph. This is normally the minimum speed at which enforcement is undertaken in all speed limits. NPCC guidance also states that whilst tolerances exist, they do not and cannot replace police officers’ discretion.”
In a different freedom of information request, North Wales Police also said it “applies the NPCC guidelines which outline the enforcement thresholds of not less than 10% plus 2mph”. Interestingly, because the Welsh Government has in recent years applied a widespread 20mph speed limit for residential roads in Wales, North Wales Police also said: “Following the change in the default speed limit, chief police officers allowed us to increase to 10% plus 4mph in 20mph limits only, meaning we start to prosecute at 26mph in a 20mph limit”.
However, even though each speeding offence with the 10% plus 2mph threshold is a matter of discretion, there are official documents which suggest that this consideration is baked into physical infrastructure and local government strategy, and not just at the mercy of individual police officers. For example, a Bedford Borough Council document on speed camera policy said there would have to be “clear evidence that… a significant number of motorists are regularly exceeding the posted speed limit” — but it considered the speed limit to be 10% plus 2mph above what the signs said.
What if you are caught by a speed camera?
The Met Police said speed cameras tend to be set to the same guidance. It said: “The minimum speed at which a speed camera is operated may be varied at any time but there are no plans to use a threshold that is not contained in the current guidance.”
However, it gets a bit more interesting here, because all enforcement cameras are calibrated in accordance with manufacturers and Home Office guidelines and you would have a legal defence against a speeding penalty if you could prove the equipment was faulty. Drivers can request the calibration certificate for the specific camera or radar gun used. Go here to read about your legal rights if you’re caught by a hidden speed camera.
