Police have clarified exactly when overtaking on the left, commonly known as undertaking, is and is not allowed under the Highway Code, following a question from a motorist about middle-lane hogging.
The clarification came after a driver asked on the official 'ask the police' website, administered by forces across the UK: "Can I overtake on the left (undertake)?"
What the Highway Code says
In their response, police first referenced rule 163 of the Highway Code, which applies to non-motorway driving and states: "Only overtake on the left if the vehicle in front is signalling to turn right, and there is room to do so. Stay in your lane if traffic is moving slowly in queues. If the queue on your right is moving more slowly than you are, you may pass on the left."
However, the regulations on overtaking on the left differ slightly on motorways. To address the question in relation to motorway driving, police referenced rule 268 of the Highway Code. It states: "Do not overtake on the left or move to a lane on your left to overtake. 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."
When undertaking is lawful
Police added: "Overtaking on the left is lawful if done in accordance with the above guidance. However, whilst there is no specific offence of overtaking on the left, if a driver undertook another vehicle, other than in the circumstances described above e.g. in the case of someone hogging lane two on a motorway, they may be prosecuted for careless driving."
Police also warned motorists to exercise "extreme care" when passing another vehicle on the left, noting that doing so could expose them to a range of hazards. As an example, officers cautioned that other road users may fail to notice you while you are overtaking, and could unexpectedly pull back towards the left.
