1 Introduction

With a top speed of 410 km/h (254 mph), the Italian Bugatti Veyron Grand Sport Vitesse is one of the fastest roadsters ever produced.Footnote 1 However, in Italy and many other counties, the legal speed limit on motorways is 130 km/h (80 mph). It is considerably lower on other roads. In urban areas, the limit is usually around 50 km/h (30 mph).Footnote 2 But it is not only sport cars from famous car companies, such as Bugatti, Ferrari, Porsche, Chevrolet and Kia, which are designed to drive considerably faster than the maximum speed that most countries permit. Almost all cars can exceed the speed limit. The authors of this article both own a car, neither of which is particularly fancy, but both of which have a top speed of approximately 160–90 km/h which is 30–60 km/h more than the maximum speed limit in our country.

Speeding is one of the main causes of traffic accidents [7], p. 229, [6], [26], pp. 391–458, [24], 509). According to a report from WHO, in 2018, there were around 1.3 million road deaths, and between 20 and 50 million people were injured (non-fatal) as result of road accidents involving all type of vehicles, cyclists, and pedestrians [30].Footnote 3 Traffic accidents are “the leading cause of death for children and young adults aged 5–29 years” [30], p. 1. A study from the European Transport Safety Council (ETSC) shows that 2100 lives could be saved every year in EU countries “if the average speed dropped by 1 km/h” [10].Footnote 4 Another study of almost 30 European countries shows that approximately 50% of all traffic has drivers exceeding the legal speed limit in it [8].

Facts such as these form the background to an ongoing and nuanced discussion among applied ethicists about where to set legal speed limits [18, 25, 31]. One question is whether, and if so how, speed limits should vary across different vehicles, including autonomous/semi-autonomous vehicles [22], non-autonomous vehicles [2], electric scooters [13], etc. Another is when and indeed whether, driving above the speed limit is morally wrong (e.g., [14, 19, 21]. These questions are important, but addressing them should not distract us from a third, and in our view, even more important question: Do we have a moral obligation to ban the production, sale and purchase of vehicles capable of driving faster than the legal limit?Footnote 5 If motorists never took advantage of their vehicles’ capacity to travel faster than the law permits, perhaps the answer would be No. However, this is not the situation. As the statistics above indicate (and many readers might have first-hand experience of motorists who drive faster than is legally permitted), drivers often speed. Again, as mentioned above, speeding causes thousands of people to be avoidably killed, and many more to be avoidably injured, every year. In light of this, we shall argue that, with some common-sense exceptions, vehicles should be required by law to have a Limited Intelligent Speed Assistant (LISA), which prevents speeding, fitted.Footnote 6 In a LISA-enabled car, it is impossible to exceed the official speed limit. The system works by limiting the amount of fuel the engine can use, meaning that when drivers depress the accelerator pedal, they cannot increase the vehicle’s speed beyond the maximum limit. Drivers cannot override this form of intelligent assistance. Driving with LISA implemented in your car is compatible with being, in all respects other than choosing to speed, fully in charge of how you drive. The driver still steers, applies the brakes, controls the lights, and so on. The only limitation is that the driver cannot exceed the legal speed limit even if the car’s engine would make this option available in the absence of LISA. In Sect. 2, we shall consider alternative strategies to limit speeding, explaining how they work.

The only publication addressing our question that we have been able to find is an article by Jilles Smids [27]. Smids defends a conclusion like ours, but it presents a different argument appealing directly to the value of reducing the number of traffic victims.Footnote 7 Our argument appeals only indirectly to this feature. Primarily, it relies on what we call the Principle of Required Prohibition (to be explained in Sect. 3). One important advantage of this principle is that it is extremely weak and therefore, we argue, acceptable across a wide range of ethical theories.

There are several less important concerns supporting mandatory installation of LISA. Here we simply want to list these. First, the avoidance of accidents aside, drivers will benefit if LISA is fitted to their vehicles by receiving fewer speeding tickets and reduced insurance premiums [1].Footnote 8 Second, it will become easier for drivers to comply with traffic law. As a result, they will be fined and jailed less (which presumably we can all agree is a good thing when it reflects a reduced number of offenses). The costs to the state of traffic law enforcement and the associated penal system will also be lower. Third, intelligent speed adaption will in general reduce speeding and speed variance. This will result in more homogeneous traffic flow, fewer queues, less stress for road users [12] and cuts in CO2 emissions [23, 29]. Fourth, crimes in which fast cars are used to escape from the police would become more difficult to engage in (assuming that, as an exception, police cars are not implemented with LISA and that criminals use cars with working LISA on them). Fifth, presumably everyone would agree that driverless cars should be designed so that they cannot go faster than the speed limit. But if that is so, why should the same restriction not apply to cars with drivers?Footnote 9 Finally, if LISA is implemented, some of the resources now being devoted to limiting speeding, such as putting up speed bumps, could be redirected to making traffic safer in other ways.

Section 2 briefly describes the technologies of speed limitation and how effective they are in reducing the number of accidents. Second 3 sets out our core argument for mandatory LISA fitting. Section 4 responds to five objections. Section 5 briefly concludes.

2 Two strategies to limit speeding

There are several strategies for combatting speeding. These include police control on the roads, speeding cameras, warning signs, speed bumps, road or lane narrowing, the education of drivers, etc. However, despite many efforts of these kinds, people still speed. Therefore, more direct strategies to combat speeding are surely worth looking at. The most obvious strategy—call it the Maximum Speed Strategy (MSS)—is to regulate the design and production of vehicles in such a way that ordinary cars can no longer exceed a certain speed limit, such as 130 km/h.Footnote 10 This strategy is already used in connection with 50 cc mopeds and the electric scooters that are available to rent in many cities around the world. The engines of such vehicles are very often designed to ensure that they cannot drive faster than law permits (for electronic scooters the speed limit is often 20 km/h, and for 50 cc mopeds it is 45 km/h). Applying a similar speed restriction to cars would have clear benefits in terms of improving traffic safety. However, this strategy also has clear limitations. Most importantly, it would not prevent car drivers from exceeding the speed limit in urban areas. This is a serious drawback since speeding in such areas involves greater risks than speeding on the highways [6].

There is an alternative strategy to MSS, the Flexible Maximum Speed Strategy (FMSS). FMSS involves fitting an Intelligent Speed Assistant (ISA) in all vehicles. ISAs use GPS data and/or traffic-sign-recognition cameras to determine the maximum speed allowed in an area. They come in many versions. The most common are the Advisory Intelligent Speed Assistant (AISA) and the Limiting Intelligent Speed Assistant (LISA).Footnote 11 AISA sends haptic, audio and visual warnings until you start driving within the speed limit, but it is still up to the driver to switch it on and comply with the AISA advice that the car’s speed should be reduced. From 2024, AISA is mandatory in all new cars and trucks in EU [11]. LISA is more proactive. Once it is fitted, the driver cannot overrule the advice or warnings given by ISA. The ISA system limits the engine’s power and thus the vehicle’s speed to ensure the legal speed limit is not breached. Studies have shown that LISA is between three and ten times more effective in reducing accidents than AISA [5, 17, 27]. It hardly needs adding that this is a significant difference.

3 The principle of required prohibition, LISA, and assault rifles

Making LISA legally mandatory in cars will save lives and reduce injuries in sustained road traffic [11, 27]. Experimental trials and field tests show that fitting LISA in all vehicles would reduce the number of fatal accidents by 25–50% (e.g., [5, 11, 20]). Given that approximately 30,000 people die in road accidents each year in the EU alone, this suggests, everything else being equal, that between 7500 and 15,000 lives could be saved each year if LISA were to be fitted on all cars in the EU [11]. In addition, the same studies referred to above show that general implementation of LISA would reduce the number of people who are injured by road accidents by around 30%. Given that approximately 1.3 million people in EU are injured each year (2017), this—again, everything else being equal—is equivalent to a decrease in the number of people injured by road accidents of almost 400,000 a year in the EU alone.

Clearly, these facts are highly relevant to questions about state regulation of the production, sale, and possession of cars. More generally, we submit that:

The Principle of Required Prohibition: If (1) through suitable legal regulation of design and production, the state can significantly reduce the harm users of a product P do to others through P’s illegal use without thereby causing comparable harms resulting from people not breaking the lawFootnote 12; (2) the relevant use of P ought to be illegal; (3) the regulation does not make any significant lawful use of P no longer possible; and (4) there is no other feasible and more efficient way of avoiding the relevant harm that users of P do others through P’s illegal use; then (5) the state ought to regulate the design and production of P to significantly reduce the harm users of P do others through P’s illegal use.

Given that P stands for vehicles, an argument with the Principle of Required Prohibition as its main premise and the claim that compulsory use of LISA in vehicles satisfies conditions (1–4) give us the conclusion that the fitting of LISA in all vehicles should be required by law.

We have already offered several reasons why (1) is satisfied in the case of LISA—most importantly, the compulsory fitting of LISA in all vehicles would significantly reduce the number of fatal and non-fatal traffic accident victims. In the next section, we shall address a couple of challenges to the idea that (1) is satisfied by LISA. We have not defended (2), which where LISA is concerned is the claim that, morally speaking, there ought to be speed limits (e.g., that it should not be permissible to drive 150 km/h in cities, thereby posing a grave risk to fellow motorists as well as cyclists, pedestrians, or simply bystanders). We think this is a claim that all or most of our readers will grant us. At any rate, we know of no country that imposes no speed limits on driving, and we are not aware of a political party—not even a stridently libertarian one—or an interest organization that promotes the cause of speed-unlimited driving. Of course, one can discuss what the speed limits should be, but this discussion is orthogonal to our argument, which can be presented on the basis of the simple assumption that the morally required speed limits are those our interlocutor believes to be morally required.

Claim (3) we defend below. As regards (4), where LISA is concerned, it is hard to be certain that there is no other feasible and more efficient way of achieving a reduction of the relevant harm drivers impose on others through illegal use of their vehicles. If for no other reason, this is because we may not yet have thought through all the alternative ways of cutting speeding. However, we can confidently say that the current alternative methods, such as speeding cameras, warning signs, and driver education, have had a limited effect, leaving us with hundreds of thousands of annual victims of illegal speeding worldwide.

Since the Principle of Required Prohibition might seem aggressively interventionist and anti-libertarian, it is worth noting just how weak (and hence plausible) it actually is. In fact, we think principles that are even more interventionist are justifiable, but to defend compulsory LISA fitting in all vehicles we have no need of these stronger principles.Footnote 13 We should stress that our principle applies to harms resulting from uses of a product that are illegal and ought to be so—not harms resulting from the uses that either are or should be legal. It also applies to harm users of the product impose on others, not harms they impose on themselves. Finally, it applies where regulation would not make any significant lawful use of the relevant product no longer possible, and where alternative harm-reducing regulation regimes are not feasible.

This means that, arguably at least, the Principle of Required Prohibition does not imply that cigarette and alcohol production should be banned. Not only does (2) appear to be unsatisfied where those products are concerned, since unlike driving at 130 km/h in cities, it is unclear that consuming a glass of wine with friends should be illegal, but (3) clearly is not met. Banning cigarettes and alcohol would negatively affect many forms of relaxation and socializing, even if it would also result in a significant health improvement for the population. It could be argued that the Principle of Required Prohibition does not even justify prohibition of the manufacture of assault rifles for sale to the public. It must be acknowledged that some will argue that while using an assault rifle to shoot at innocent people is and should be illegal, the possession of such a firearm, and its use to protect oneself from culpable aggressors, should be legal. Forbidding the manufacture and sale of assault rifles would eliminate this significant and (in many US states) lawful use of assault rifles in such a manner that (3) is arguably not satisfied in the case of such rifles. But now consider:

Limiting Targets Assistant: AI engineers develop an inexpensive mini-computer that can easily be fitted to all assault rifles. The computer blocks the rifle when the shooter wants to fire it at an innocent person, and more widely when the rifle is used for another illegal purpose, but it does not block the rifle from shooting when the target is a legal one, as it would be when a culpable aggressor is about to attack the person with the assault rifle life-threateningly.

Of course, there are no such smart assault rifles on the market. The point we want to make by presenting Limiting Targets Assistant (LTA) is that if such smart assault rifles could be produced and sold, then according to The Principle of Required Prohibition—and in our view very plausibly so—the state should outlaw production of conventional assault rifles which, unlike LTA rifles, can be used for various illegal purposes.Footnote 14 Admittedly, those who want an assault rifle that can be used for illegal purposes but have no intention of acting illegally might complain that banning conventional assault rifles frustrates their strong desire to possess such a rifle. However, that complaint does not seem to have much moral weight. First, one might question whether a desire to be able to do something that is, and should be, illegal carries any moral weight at all. Second, even if we agree that the desire carries some moral weight, it seems that in comparison with the concern to avoid people being subjected to death and serious injury its weight is limited. Surely, few of us would think that my interest in having a lab capable of producing weapons-grade anthrax (and in the absence of my actually producing any such anthrax) is sufficiently significant for it to outweigh the public interest in banning the establishment and ownership of such labs.Footnote 15

If these two points are accepted, the question becomes: In what way, if any, is our hypothetical LTA technology different from the actual LISA technology? If we agree that something like The Principle of Required Prohibition shows that, and helps to explain why, the state should not allow the manufacture and sale to the public of conventional assault rifles, when instead people could buy, own and use smart LTA assault rifles, should we not similarly agree that the state should not allow the production of cars that can be used to exceed speed limits, creating an excessive risk of death or injury to other people, when instead people could buy, own and drive smart LISA cars that would prevent them from speeding, limiting the risks they pose to others?

Admittedly, there are differences between the two cases. For one thing, firing an assault rifle at an innocent person comes with a high likelihood of causing death and (if they are lucky) less than fatal harm to them. Relatively speaking, driving over the legal limit is less likely to result in death or injury to innocent bystanders (it depends of course on how fast you drive, and where). However, we deny that these differences justify treating the two cases differently. Specifically, regarding the difference just mentioned, we would like to point out that, intuitively, we would not think differently about the regulation of assault rifles if the risk of death and injury from their use was lower—e.g., because the world in question is one in which people wear protective Kevlar gear. Moreover, there are countervailing factors favoring LISA cars more strongly than LTA assault rifles. Most importantly, motorists very often speed, whereas rifle owners only very rarely fire them at others, and this means that, from a purely pragmatic point of view, speeding is a much more urgent regulatory issue than shooting, other things been equal.

4 The fast and the suspicious: arguments against LISA

The previous section contains our positive argument for the conclusion that LISA should be mandatory in law. In this section, we respond to five challenges to this conclusion. First, some have argued that LISA would introduce novel risks, as we sometimes need to exceed the speed limit in ways that increase road safety (e.g., [22].Footnote 16 Overtaking, for example, would become more dangerous, as the technology may prevent the driver from accelerating to a sufficiently high speed to overtake a car without running into oncoming drivers [15]. Therefore, mandatory fitting of LISA does not satisfy (1) in the Principle of Required Regulation.

This is a real concern, but we think it has insufficient weight to overturn our argument. When introducing a new technology, we cannot know for sure what will happen, but this should not make us stop the introduction of new technology if we have strong reasons to believe that the risks of negative outcomes are by far outweighed by the positive outcomes.Footnote 17 Safety vests on ferries introduced the risk that passengers would suffocate from misapplying them, e.g., by getting the attached straps around their neck and the like. However, the fact that making safety vests mandatory on ferries introduced this novel risk was (and is) not a good reason on balance to decline to introduce them, since the risks eliminated in this case—of drowning in an emergency—are far graver than the novel risks introduced. Research since the 1990s has shown that the risks of associated with LISA are very low, and that the rewards of requiring it to be fitted by law would clearly outweigh them ([27], p. 213). Furthermore, car simulator experiments suggest that drivers in cars fitted with LISA will tend to adjust their driving by overtaking less (Jamson et al., p. 22). Supplementary and mandatory programs educating drivers about when it is safe to overtake in a car with the LISA system could be run (Jamson et al., p. 22). Finally, if LISA is combined with a system that “… would assist drivers in judging the safety of gaps in the oncoming traffic stream, by means of a simple interface. Such a support system could provide a valuable feedback mechanism for drivers regarding the safety of overtaking opportunities and, if combined with a mandatory ISA, could realize the traffic safety benefits reported elsewhere” ([12], p. 22).Footnote 18

Second, Brownsword [3] worries that the fitting of LISA to most vehicles would erode the moral agency and moral responsibility of drivers. Indeed, he believes that what he calls “techno-regulation”, of which LISA is an example, in designing out the option of agents inflicting harm on others, makes us passive moral agents “… that are no longer active participants in a moral community” [3], p. 19).

In response to this, we note first that while LISA reduces drivers’ moral agency in speeding, the moral agency of the driver is still genuine. Drivers of LISA cars are, within the legal speed limit, still in full control of overtaking, tailgating, and deciding to be or simply being inattentive in ways that leave the option of harming people intact ([27], p. 215).Footnote 19 Second, to the extent that mandatory implementation of LISA would involve a small cost in the form of limited erosion of the driver’s moral agency, this might be worth it. Indeed, it would seem morally indecent to insist on the avoidance of a small reduction of drivers’ moral agency at the cost of the deaths of thousands of people each week ([27], p. 215). Similarly, it would be morally outrageous of the owners of assault rifles to resist, on grounds of the protection of their moral agency, mandatory fitting of Limiting Targets Assistants on their assault rifles—e.g., in the presence of the infamous school shootings involving assault rifles with which we are all too familiar. Indeed, it seems problematic to assign any moral weight at all to the preservation of an illegal option to engage in activities that are very risky for other people.

Brownsword’s argument also seems to show too much. Suppose cars could be redesigned so that they could not be stopped by traffic barriers erected to protect pedestrians (one sees these in cities now, around buildings vulnerable to terrorist attack). On Brownsword’s view, such redesign would boost the moral agency of drivers, since it adds a morally unacceptable alternative to their set of options which, exercising moral judgment, they choose not to take. Clearly, though, this would not justify redesigning cars in this way. There are good reasons why we want cars to continue to be built in such a way that they can be stopped by traffic barriers. The same is the case, we would argue, with building cars so that they cannot travel faster than the speed limit.

A third concern, also raised by Brownsword [3], is that the implementation of LISA for safety reasons is the first step on a slippery slope that leads to a totalitarian society like the one described by George Orwell in his book 1984, in which the state uses technology extensively to regulate citizens’ behavior in detail.

To our mind this worry about the potentially harmful effects of implementing mandatory LISA is speculative and, unlike the clear and immediate benefits of implementing LISA, undocumented. It is important to remind ourselves that the state already regulates products in all sorts of ways with an eye to preventing us from using them in ways that cause harm to others. Typically, we are accustomed to these regulated products. We embrace them and certainly do not worry that we are on a slippery slope leading to a totalitarian society. Few of us think that road barriers preventing motorists from driving down a pedestrian street are a dangerous concession potentially driving us in the direction of illiberal societies like Nazi Germany, the USSR, etc. Finally, it is worth keeping in mind that totalitarianism is first and foremost about what the laws say (assuming there are laws) and not about making citizens accept these laws. Indeed, one could imagine raising the legal speeding limits, making installation of LISA mandatory, thus, as a consequence reducing speeding and, thus, the number of traffic victims. It strains credibility to think that this would put us on to a path toward a techno-totalitarian society.

Fourth, mandatory fitting of LISA would make vehicles more expensive. Some drivers might even be unable to buy vehicles as a result. This, it might be argued, unjustly disadvantages them relative to other drivers. Presently, fitting LISA hardware (including camera, brackets, trim and wiring) costs between €186–249 per vehicle.Footnote 20 If LISA were to become mandatory, economies of scale would probably lower the costs of LISA. Moreover, the risks involved in speeding are not equally distributed: disadvantaged people who cannot afford to buy a vehicle are subjected to them without enjoying the benefits associated with its being permissible to impose this risk on others. Similarly, every fourth traffic victim is a cyclist or a pedestrian. Yet they pose little or no serious threat to others through their chosen means of movement [27], 207–208). Hence, the appeal to fair distribution of benefits and burdens by those opposing mandatory installation of LISA backfires: it also serves as an argument against not addressing these unequal risks. Finally, mandatory installation would, as we pointed out above, result in a range of cost savings—e.g., on emergency services, hospitals, insurance premiums. Surely, these savings could be used to subsidize the roll out of LISA to the point that the present pragmatic concern is met.

Fifth, and finally, some might contend that mandatory fitting of LISA will not help much because drivers who want to speed are likely to tinker with, or pay others to tinker with, their speed limitation systems to enable them to drive faster than the speed limits permit—or make other adjustments if they are otherwise dissatisfied with how the system functions [4]. In support of this contention, they might point out how many (especially young) users of 50 cc mopeds have them altered so that they are capable of going faster than they were designed to go.

If the mandatory fitting of LISA were to make no difference to speeding, the case for the scheme would fall apart. However, the antecedent here is very implausible. The great majority of 50 cc mopeds have not been tinkered with, and whereas “tuning” 50 cc mopeds involves a relatively simple mechanical intervention, tampering with LISA might well be beyond the capabilities of all but a few trained mechanics with supplementary courses in electronics and software. Finally, how ineffective the LISA technology becomes is likely to depend on the fines for tampering with it, and more generally how stringently the prohibition on cars without LISA is enforced. On the latter issue, we note that, in many countries, by law cars need to be checked regularly by authorized mechanics, and that such checks could easily reveal if the LISA system has been adjusted.Footnote 21

5 Conclusion

We have argued that the speed of private vehicles—not emergency vehicles (such as police cars, ambulances, and fire engines) should be restricted by mandatory fitting of LISA. Our argument rests on a normative principle, the Principle of Required Prohibition, and on various empirical premises regarding the effects of mandatory fitting of LISA and alternative means of reducing illegal speeding. We have argued that the Principle of Required Prohibition is surprisingly weak in the sense of being very undemanding and, thus, should be accepted by most if not all of us, and we have appealed to various research reports to support the empirical claims we have made. Finally, we have rebutted five objections to the legal prohibition of cars without LISA. Our conclusion is that the state should make it impossible for drivers to illegally violate speed limitations by making the installation of LISA on cars compulsory by law, just as the state, in many other ways, renders it impossible, or at any rate harder, for us to violate laws.Footnote 22 The case for mandatory LISA is, in all essential respects, just like the case for road barriers that prevent motorists from driving on streets reserved for pedestrians, or (to take a rather different issue) the case for withholding taxes at source, thus depriving citizens of the opportunity to under-declare their income and evade taxes they are required to pay by law.