Autonomous vehicles – the criminal law perspective

The legal framework which has developed gradually over the last 100 years since the invention of motor vehicles governs the criminal liabilities of drivers. The system is well understood and is managed reasonably well by our overburdened criminal courts when drivers fall foul of the law.

Regulatory review

This system is set to undergo a major test with the growing drive towards the development of autonomous vehicles (AVs). The government is taking steps to prepare the way for AVs in the UK and a three-year review of the regulatory framework is currently underway. In November 2018, the Law Commission of England and Wales and the Scottish Law Commission published their preliminary consultation paper for the safe deployment of AVs in the UK. The consultation closed on 19 February 2019 and publication of the findings is awaited.

Criminal responsibility of the user-in-charge

In our response to the consultation we pointed to some of the complex issues which will have to be addressed at an early stage and kept under review as the technology evolves. This includes clarification of the role of the ‘user-in-charge’, who will operate the controls of the AV when the vehicle is not in autonomous mode. Key issues in respect of criminal responsibility of the user-in-charge, include:

  • In semi-automated vehicles, the driver would be expected to monitor the driving task and should accordingly continue to be subject to specific criminal offences arising from this task, but with vehicles in fully-autonomous mode (even with hand over and hand back) things become far more problematic.
  • The user-in-charge should not be held criminally responsible for the vehicle whilst it is in ‘fully autonomous’ mode. It would be wrong to impose a legal duty on a user-in-charge to act or take steps to act in an emergency situation when the vehicle has been designed to operate without any input or oversight from the user-in-charge who may, for example, be permitted to be seated facing away from the direction of travel.

    It may prove very difficult to legislate for a criminal ‘act of omission’ offence in this scenario as there is no act of omission. A user-in-charge should be entitled (together with other passengers) to place reliance upon autonomous systems when a vehicle is correctly in autonomous mode. The same would be true in an AV which does have hand-over and hand-back, but where there was no reasonable opportunity for the user in charge to take back control in time using the prescribed method and systems for handback.
  • If there is a clear risk and the vehicle in autonomous mode is not taking steps to avoid that risk, the user-in-charge may have some opportunity to take back control of the vehicle and avoid those risks. However, assessing whether the-user-in charge could do that would be highly fact-sensitive and may be dependent upon the technology of the vehicle and how it has been programmed to hand back control.

    We believe the onus on the user in those circumstances would be far lower than say with the driver of a manual vehicle forced to take an avoiding manoeuvre due to the wrong behaviour of another road user. If there was no reasonable opportunity for a user in charge to get back manual control in time, then there can again be no act of omission and it is hard to see how it would be right to attribute any criminal culpability to the user in charge.
  • Following on from the above points, it may be possible to construct criminal culpability on the basis of an act of omission. For example, in circumstances where a vehicle in autonomous mode is trying to hand back control, the user in charge is either negligently or deliberately refusing to take back control, had reasonable time to do so and did not, and then a road accident occurs. However, again there are evidential and other difficulties and it is so fact-sensitive. Was the autonomous system reasonable in all the circumstances in trying to hand back control and did it allow a reasonable amount of time for the user to take back control? If not, again, how can there be any act of omission.


When considering whether a user-in-charge should be held to be criminally responsible, there will be numerous subjective factors in respect of each incident which will prevent the situation from being clear-cut. This includes:

  • The information that was being conveyed by the vehicles systems to the user-in-charge immediately prior to the incident
  • What was visible to the user-in-charge
  • Whether there were any built-in systems which operated to override the manual input from the user-in-charge.

The importance of the interplay between technology and manual interventions is of crucial significance, as we are learning from recent air disasters involving flight control issues.

When the vehicle is in autonomous mode, the responsibility for the vehicle should rest with the automated driving system entity. However, will the user-in-charge be held responsible under criminal law if, for example, the vehicle exceeds a temporary speed restriction? Whilst smart motorways are being rolled out across the country and may share data with AVs so that the speed can be adjusted as necessary, we are a long way from the point of having such a system rolled out to our entire road network.

The allocation of criminal responsibilities in respect of vehicles which are intended to be operated without a user-in-charge is also a complex matter which needs to be carefully considered.

Even after the development of robust legislation which adequately provides for AVs, the timeline for the introduction of AVs will need to factor in training for criminal judges on the new legislation. In addition, the undoubted rise in the need for expert evidence to be given in criminal trials will also lead to lengthier criminal hearings.

Whilst there is a desire for the UK to be at the forefront of this new technology, proper consideration should be given to the additional strain that this will necessarily place on the criminal courts system.

Read other items in Health, Safety and Environment Brief - April 2019

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