Defining Self-Driving Vehicles: Resolving the Ambiguity in Legislation

Private vehicles with the ability to perform driving tasks typically undertaken by the person behind the wheel are increasing in their prevalence on public roads. These connected and autonomous vehicles (CAVs) are frequently referred to through terminology including ‘autonomous’, with manufacturers selling additional functionality with reference to ‘full self-driving’ capability. The reality is that whilst the technology underpinning such vehicles in advancing driver assistance is significant, there exists international concern about the uncertainty in their definition which may mislead consumers as to the efficacy of an autonomous car. This uncertainty may be open to abuse by some users, and has led to manufacturers advertising ‘puff’, overstating the functionality of their CAV. In our article, we examine these issues and conclude that the UK legislation facilitating the use of CAVs, the Automated and Electric Vehicles Act 2018, requires urgent legislative guidance to regulate these definitions in an effort to protect all stakeholders.

Overreliance on autonomous features

There is a general lack of agreed standards and descriptions of what ‘autonomous’ driving means, at least on a legislative basis if not, as will be discussed later, an engineering one. The result has been little guidance on and regulation of the use of this and associated terms, leading directly and indirectly to numerous incidents of CAVs being involved in accidents when used in autonomous driving modes and the addition to the lexicon of the term ‘autonowashing’ coined by Liza Dixon. Consumers’ confusion here is not entirely their fault. A tweet from Tesla CEO Elon Musk as recently as 2019 advertised how a Tesla car drove without the need for human input, and he has repeatedly overstated the capabilities of vehicles in ‘full self-driving’ modes. Hence ‘autonowashing’ exists where marketing descriptions of vehicle automation affects user perceptions of the vehicle’s capabilities (often misleading the public). It leads to such capabilities often being overstated, with the result that, especially in the advent of social media platforms, trust is misplaced in these vehicles and users misuse or override safety features.

The definitional dilemma in other jurisdictions…

In the US, the National Highway Traffic Safety Administration designated CAVs as vehicles for which at least some aspects of a safety critical control function (for example, steering, acceleration, or braking) occur without direct driver input. In Canada, Transport Canada, part of the federal ministry, has defined autonomous vehicles as those that ‘use a combination of sensors, controllers and onboard computers, along with sophisticated software, allowing the vehicle to control at least some driving functions, instead of a human driver (for example, steering, braking and acceleration, and checking and monitoring the driving environment).’ The inclusion of the passages ‘… control at least some driving functions’ and ‘… checking and monitoring the driving environment’ are likely to cause confusion given that Transport Canada considers autonomy to be a situation where the driver or person behind the wheel relinquishes some of their authority with respect to driving functions to the vehicle itself. Naturally, the word ‘some’ is concerning when looking for a precise definition of autonomous, either in the advertisement of an attribute of the vehicle or the timing of its use, and it has further implications for the potential culpability of an individual who rests power to such a feature.

… and in England and Wales

The Automated and Electric Vehicles Act allowed for the use of CAVs by establishing a system of compulsory insurance to protect drivers and third parties in the event of accidents involving vehicles in autonomous modes. To determine which vehicles would be covered by the Act, the Secretary of State was tasked to ‘…prepare, and keep up to date, a list of all motor vehicles that—may lawfully be used when driving themselves, in at least some circumstances or situations, on roads or other public places in Great Britain.’ The Act identifies ‘automated vehicle’ under section 1(4) as ‘a vehicle listed under this section’ and continues under section 8(1)(a), that ‘… a vehicle is “driving itself” if it is operating in a mode in which it is not being controlled, and does not need to be monitored, by an individual.’ These sections of the Act immediately raise issues which require clarification.

First, nowhere within the Act is it defined what an automated vehicle is for the purpose of this piece of legislation. Secondly, the instruction to the Secretary of State of maintaining a list of motor vehicles that may be used when driving themselves does not identify what ‘driving themselves’ actually means. According to section 8 the vehicle is ‘driving itself’ only when it is not being controlled and does not need to be monitored (authors’ emphasis) by the individual. Given that no private vehicle presently available for use on roads in the UK operates without the driver having to monitor it and be ready to take control means that the very legislation currently permitting the use of autonomous vehicles does not apply to the current suite of CAVs. The Act does not offer gradations of autonomy, does not refer to international standards of what ‘autonomous’ is and when it will apply and, therefore, until vehicles on UK roads operate at Levels 4 and 5, such vehicles are not autonomous vehicles. Further, the definitional discrepancy permits marketing terms to be used which might operate to confuse the uninitiated user and place them at risk as to the limits and (possibly) lawful use of this feature.

The Society of Automotive Engineering definition: An internationally ready model

To circumvent the current lacunae in defining key terms such as ‘self-driving’, ‘driving itself’, and ‘autonomous’ as found in the Automated and Electric Vehicles Act, we suggest in our article that the UK follow Germany and the US with ‘autonomous’ being restricted to a Level 4 or 5 driving automation system according to Society of Automotive Engineering International Standard J3016. The Society has an internationally accepted grading system denoting the stages, beginning at driver assistance features (Levels 0-2), partial automation (Level 3) to high (Level 4) and finally fully autonomous vehicles (at Level 5). CAVs on UK roads currently operate at Level 2 (moving to Level 3 later in 2021), while true automation occurs at Level 5 where the automated system performs all driving tasks across all driving modes and adheres to International Standard J3016.

Using these definitions results in an internationally accepted description covering the entire range of driving automation features in a functionally consistent and coherent manner. Thus, were national legislation to take this agreed Standard and incorporate it as an amendment to existing legislation or as part of a broader interpretative scheme, the existing ambiguity and generality of when a vehicle is in autonomous mode could be removed.

James Marson is a Reader in Law at Sheffield Hallam University.

Katy Ferris is an Associate Professor in Business Law at the Nottingham University Business School.


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