Overtaking on the left, commonly known as "undertaking," can result in prosecution for careless driving, carrying a fixed penalty of £100 and three points on a driver's licence. The police have clarified their position on the practice, which many drivers consider justified when faced with lane hoggers in the middle or outside lanes.
Rule 268 of the Highway Code states: "Do not overtake on the left or move to a lane on your left to overtake." There are two specific exceptions: if traffic is moving slowly in queues and the queue on your right is moving more slowly than you are, you may pass on the left; and if the vehicle in front is signalling to turn right.
Police position on undertaking
The Ask The Police website, an official police resource, says: "Overtaking on the left is lawful if done in accordance with the above guidance." While there is no specific offence of "undertaking," the police state that "whilst there is no specific offence of overtaking on the left, if a driver undertook another vehicle, other than in the circumstances described above, eg in the case of someone hogging lane two on a motorway, they may be prosecuted for careless driving."
If the offence is considered serious, it may be dealt with through the courts, where offenders could face higher penalties. Drivers do not have to be caught in the act by police either; fellow drivers can submit video evidence via Operation Snap, a police initiative used across various UK police forces that allows the public to report driving offences digitally.
When overtaking on the left is allowed
Rule 268 also states that "in congested conditions, where adjacent lanes of traffic are moving at similar speeds, traffic in left-hand lanes may sometimes be moving faster than traffic to the right. In these conditions you may keep up with the traffic in your lane even if this means passing traffic in the lane to your right. Do not weave in and out of lanes to overtake."
Rule 163 contains similar guidance but adds that you can "overtake on the left if the vehicle in front is signalling to turn right, and there is room to do so."
Why passing on the left is dangerous
Police explain the most obvious reason for not overtaking on the left: "Other drivers may not see you and suddenly move back to the left." Popular TikTok account Big Jobber, which gives advice on driving rules, says: "There is a very good reason why this is a 'two wrongs don't make a right' situation. How often do you see a middle lane hogger moving dangerously from the middle lane to the slip road without checking that it's clear and safe to do so?"
Big Jobber adds that in the UK, right-hand side (off-side) safety checks are emphasised more than left-hand side (near-side) checks, because the default driving position is to the left-hand side. "Passing on the left creates a hazard, it increases the risk of a collision and can be extremely dangerous and potentially fatal," they said.
