Police Enforcement

Last year someone sent me the following email question :-

You offer assistance with any claims by police forces that 20mph limits (zones?) are not enforceable. Any advice concerning the following would be appreciated.
The County Councillor was recently reported as saying that the police have advised him that the local 20mph zone is not enforceable and the only action that can be taken is to charge a motorist exceeding the 20mph limit with dangerous or careless driving. Currently he is refusing to explain his remarks. The minutes of a recent meeting of the parish council record ”due to recent changes in legislation/regulation the Parish Council may apply for enforceable action against speeding in the 20mph zone” and “Update from Police: Recent change in legislation has enabled enforcement codes for individual 20mph zones to be applied for”. Currently the chair of that meeting is unable to explain what was meant. Does any of this mean anything to you?

I am aware of the ACPO Speed Enforcement Policy Guidelines and DfT Setting Local Speed Limits. Currently it seems like a ‘smoke screen’ so any clue to the meaning of these statements and any guidance concerning how to question these statements would be appreciated

My answer follows 

We have a long held policy in this country that :-

  • Elected representatives of the community sets laws
  • A professional police force enforces the law
  • An independent judicary sentences offenders



For a 20mph limit to be enforceable there are 4 requirements :-

1. A relevant Traffic Regulation Order

All speed limits, other than those on restricted roads, should be made by order under Section 84 of the Road Traffic Regulation Act 1984. Any speed limits below 30 mph, other than 20 mph limits or 20 mph zones, require individual consent from the Secretary of State. Unless an order has been made and the road is signed to the contrary, a 30 mph speed limit applies where there is a system of street lighting furnished by means of lamps placed not more than 200 yards apart.

Note that there are no regulations regarding how to set a local speed limit. However, the Dept for Transport does provide guidance and this is available here 

Hence the Traffic Authority must make a Traffic Regulation Order to set the speed limit at 20mph. This includes publishing the order so that those affected may object if they wish.

2. Appropriate signing

In order that drivers are aware of the changed speed limit then the appropriate signage must be provided. These are regulations and must be adhered to. The regulations are slightly different for 20mph zones and limits but both must include the appropriate boundary signs where speed limits change and any point in the limit must be no further than 50m from a repeater sign, roundel or physical calming device. Note that since 2016 the frequency of repeater signs has been at the discretion of the Traffic Authority.

3. Length of road, sighting, equipment

In order for the police to enforce a limit then they require a clear distance for them to observe drivers and for drivers to see them. This may  make certain sites less suitable for speed detection. Different measurement equipment are available. Whilst in the past some "radar" based speed detectors were not approved for use below 30mph, most forces have "laser" type devices that are fully approved for use at 20mph.

4. A Police Force that is willing to enforce

This may seem obvious, and whilst police are becoming far more supportive of 20mph limits and their enforcement, it is clear that in some forces there is a reluctance to enforce. This may be as a result of individual police not understanding the law or a reluctance to commit resources. However as long as the above three conditions have been met then there is nothing to prevent action by the police.

Recently the Association of Chief Police Officers has re-iterated the fact that 20mph speed limits are enforceable and where the limit is clearly marked (ie meeting signage regulations) then any offenders may be prosecuted. The police have also developed the option of speed awareness courses for those exceeding 24mph in a 20mph limit and these may be an option in some forces. Fixed Penalty Notices and prosecutions can also be used. In addition "light touch" enforcement can also be used which merely constitutes a reprimand/talk rather than anything more formal.



I would suggest that the comments about regulations in your question are internal practices within your police force or county council and are not imposed by any outside body. Let there be no mistake, 20mph limits are enforceable and are being enforced by many police forces in the UK.

For a guide on how local authorities can work best with police and other bodies to maximise compliance then see our briefing sheet here

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