Prosecution for undertaking or middle-lane hogging

This is a question that comes up surprisingly often, so let me set out the legal position clearly.

Middle-lane hogging:

Since 2013, middle-lane hogging has been explicitly targetable by the police as a careless driving offence. It falls under section 3 of the Road Traffic Act 1988, which makes it an offence to drive a motor vehicle on a road without due care and attention, or without reasonable consideration for other persons using the road.

Rule 264 of the Highway Code states that you should always drive in the left-hand lane when the road ahead is clear. If you are overtaking a number of slower-moving vehicles, you should return to the left-hand lane once you are safely past. The key change in 2013 was that the police were given the power to issue fixed penalty notices for this behaviour rather than having to pursue a full prosecution, making enforcement more practical.

The fixed penalty is currently 3 penalty points and a 100 pound fine. In more serious cases, or where a fixed penalty is contested, the matter can go to court, where the maximum fine for careless driving is unlimited and a discretionary disqualification is available.

Undertaking:

Undertaking, meaning passing another vehicle on the left, is not a specific standalone offence under the Road Traffic Act 1988. However, it can amount to careless or even dangerous driving depending on the circumstances.

Rule 268 of the Highway Code says you should not overtake on the left or move to a lane on your left to overtake. However, Rule 268 also recognises exceptions. You may pass on the left in slow-moving traffic when queues in lanes to the right are moving more slowly than you, and you may stay in your lane if traffic is moving slowly in queues and vehicles in a lane to the right are moving more slowly.

So the question of whether undertaking is an offence depends heavily on context. If you swerve sharply into the left lane at speed purely to get past a middle-lane hogger and then cut back across, that is likely to be treated as careless or even dangerous driving. If you simply maintain your speed in the left lane and happen to pass someone who is hogging the middle lane, that is much less likely to result in any enforcement action.

Practical reality:

In practice, enforcement of both middle-lane hogging and undertaking is relatively rare. The police tend to focus on genuinely dangerous behaviour rather than issuing large numbers of fixed penalties for lane discipline. That said, if you are observed doing either and it is recorded on dashcam or police camera, there is a real risk of a fixed penalty notice or prosecution.

The safest legal position is to drive in the left lane unless overtaking, overtake on the right, and return to the left lane once you have passed. If someone is hogging the middle lane, the legally safest approach is to overtake them on the right, even if that means moving to the outside lane to do so.

If you have been stopped, reported, or issued a fixed penalty for either of these, the specific facts matter a great deal, including speed, road conditions, traffic density, and whether there is any footage.