A Constitutional Right to Drive? Green Mobility and the Limits of Individual Freedom

1. Introduction

1.1. The Context and Significance of the Topic

Road transport remains the single largest source of greenhouse gas emissions within the European Union’s transportation sector, and the decarbonization of mobility has now become almost a policy obsession [1]. The toolkit employed by governments is well known; low-emission zones, deadlines for phasing out internal combustion engines, and subsidies steering consumers toward electric vehicles [2,3]. No one seriously disputes the environmental logic behind this. At the same time, however, each measure quietly restricts what individuals can do: which streets they can drive on, what kind of vehicle they can own, and whether they can even afford to continue driving at all. It is this narrowing that gives rise to the constitutional problem. Mobility is closely intertwined with autonomy, employment, and the smooth running of daily life in general—a dependence that sociological scholarship has theorized through the paradigm of “automobility,” the socio-technical system in which car use becomes constitutive of everyday social participation rather than a mere transport choice [4,5]; thus, restrictions on driving almost never affect a single constitutional right in isolation. Typically, they affect multiple rights at once [6], and the scholarly literature—as the following overview shows—has not always kept pace with this reality.

1.2. Climate Constitutionalism and Individual Mobility: Tensions in the Literature

The scholarly literature on climate constitutionalism can be broadly divided into two strands. One examines how states’ mitigation obligations have expanded over time [7]. The other describes the so-called “rights turn” in climate litigation [8]—the phenomenon whereby courts are increasingly willing to treat weak climate policy as a fundamental rights issue rather than as a matter best left to legislation and elections. This is a significant shift, supported by the numbers: by the end of 2024, the number of climate lawsuits worldwide had risen to nearly 3,000, spanning some sixty jurisdictions [9]. This body of scholarship has itself been the subject of systematic literature review, which confirms both the rapid growth and the increasing interdisciplinarity of climate litigation research [10].

The most illustrative example of this remains the Grand Chamber judgment in the case of Verein KlimaSeniorinnen Schweiz and Others v. Switzerland. In this case, the European Court of Human Rights (ECtHR) held that Article 8 of the Convention provides genuine protection against the harmful effects of climate change, and that a state that fails to establish an adequate legislative framework for mitigation simply exceeds its margin of appreciation [11,12]. This is a strong statement from a court that is typically characterized by caution.

Another strand of the literature looks beyond mitigation obligations and turns its attention to freedom of movement and property. Article 2 of the Fourth Additional Protocol to the Convention guarantees freedom of movement within the territory of the state [13], which the courts have interpreted quite consistently as protecting the very possibility of movement itself, rather than any specific means of doing so. This would be fine—except that a motor vehicle is property. If its use is restricted, then—regardless of whether the courts always state this explicitly—the analysis in fact enters the realm of Article 1 of the First Additional Protocol [14]. And when it comes to property, the Strasbourg Court has traditionally granted states broad discretion, particularly when the justification is of a social or environmental nature, as demonstrated by the case of James and Others v. the United Kingdom [15].

It is precisely at this point that the scholarly literature becomes, in the author’s view, inaccurate. The Neubauer, Urgenda, and KlimaSeniorinnen cases are almost reflexively cited as a single, converging line of reasoning that supposedly confirms that states are subject to positive climate protection obligations. However, these are not cases of the same type. The Dutch Supreme Court prescribed a specific, quantified reduction target. The German Constitutional Court, by contrast, found structural deficiencies in the legislative framework without specifying any numerical targets. Strasbourg, constrained by the principle of subsidiarity, remained even more restrained. Thus, the German approach is in fact more interventionist than the Swiss one—and this difference raises questions regarding constitutional limits that have received little attention in the literature, questions that become even more acute when the analysis moves away from abstract emissions targets and turns to actual restrictions on driving—and this is precisely the direction taken in this study. Similarly, the consensus in favor of regulatory intervention itself cannot be left unquestioned. Climate constitutionalism tends almost by default toward greater intervention, but critics have a point: strict restrictions on private vehicle ownership can undermine socioeconomic mobility, especially in rural areas where there are no real alternatives to driving, a pattern documented in the broader transport-poverty literature [16,17]. Ignoring this distributional aspect risks labeling a restriction as “proportionate” simply because it works on average—while quietly imposing a disproportionate burden on precisely those who have the fewest options.

These positive obligations, incidentally, are not limited to the framework of the Convention. In its 2021 climate protection ruling, the German Federal Constitutional Court held that even a weak climate policy can violate fundamental rights—since it shifts a disproportionately large share of the mitigation burden onto generations not yet born [18]. The Dutch Supreme Court essentially reached the same conclusion in the Urgenda case [19].

In virtually all European legal systems, proportionality is the mechanism that resolves this tension between rights and environmental protection objectives. Courts systematically ask the following questions: Is there a legitimate objective? Is the measure appropriate? Is it necessary? And, all things considered, is it proportionate in the strict sense? Four questions, a single test—which, however, is applied with strikingly different levels of strictness depending on which court is reviewing the case, consistent with the broader theoretical account of proportionality as the balancing of constitutional rights conceived as optimization requirements [20].

1.3. Research Gap

There is a gap between these two strands of literature. The literature on states’ climate protection obligations and on mobility rights has developed independently of one another, and neither has attempted to compare transportation restrictions using measurable technical or economic indicators. Research on low-emission zones remains at the level of air quality and policy, while the literature on climate constitutionalism remains at the level of general mitigation obligations. The narrower issue—specifically, the issue of restrictions on the use of private vehicles—falls into the gap between these two. To the author’s knowledge, no study to date has combined dogmatic constitutional analysis with quantified proportionality metrics to examine whether green mobility restrictions can be justified, and if so, under what conditions.

1.4. Objectives and Hypotheses

This study attempts to bridge this gap by combining comparative constitutional analysis with quantitative policy data to examine whether there is a right to drive, and if not, what rights are at stake in the case of green mobility restrictions, and under what conditions such restrictions are justified. The study is guided by two research questions: (Q1) Does any of the constitutional systems examined recognize the right to drive a private motor vehicle as an independent constitutional right? (Q2) If mobility restrictions affect property rights, economic freedom, or freedom of movement, do Europe’s current green mobility measures pass the four-part proportionality test?

The added value of the study lies precisely in this integration: combining constitutional law doctrine with quantified technical, economic, and litigation data is an approach that has not previously been systematically applied in the debate on mobility rights.

One distinction is worth noting at the outset, as it runs throughout the entire study. Restrictions that merely dictate how someone may drive—a toll system, a technical requirement, a rerouted street segment—leave the activity itself untouched. These are relatively easy to justify. Restrictions, however, that effectively cut off access to personal mobility are of an entirely different nature: they preclude an existing use of property and therefore must be subject to significantly stricter scrutiny. This distinction is explained in more detail in the Discussion and applied in the Results.

2. Materials and Methods

2.1. Sources and Data Collection

The study rests on two pillars: constitutional analysis and the quantitative analysis of secondary policy and litigation data. On the legal side, the material comprises the relevant provisions of international treaties, EU secondary legislation on the decarbonization of transportation [21,22], Hungary’s Fundamental Law [23], and the case law discussed in the Introduction and Discussion. This material is not examined in a vacuum: it is compared with quantitative data from official and peer-reviewed sources, namely the European Environment Agency’s mobility indicators [1], the Clean Cities Campaign’s database on low- and zero-emission zones [24], an empirical study examining the compliance and choice effects of London’s Ultra Low Emission Zone (ULEZ) [25], and the Grantham Research Institute’s global climate policy database [9].

2.2. Analytical Framework

Three regulatory instruments stand out among the data, and these form the focus of the study: low-emission zones, the phase-out schedule for internal combustion engines, and congestion charges. Each of these is subjected to the four-part proportionality test described in the Introduction, drawing on the case law and compliance data presented in the Results to conduct the sub-tests for suitability, necessity, and strict proportionality.

It is important to clarify the scope of the analysis: the test is applied to the measures themselves, not to how a particular authority enforces them on a specific day. This reflects the way courts generally approach climate and mobility legislation. Suitability and necessity are assessed based on aggregated technical and environmental indicators—compliance rates and emissions reductions. Strict proportionality, by contrast, relies more heavily on economic and electoral data.

2.3. Validation and Reliability

No claim in this study relies solely on a single source; this is the result of a deliberate methodological decision. Reliability is ensured by cross-checking multiple independent data sources: official EU and EEA statistics, a low-emission zone database maintained by an industry player, peer-reviewed research on compliance and policy impacts, and a recognized academic litigation database. Legal claims were compared with the original court rulings and legislative texts, rather than with secondary summaries of them. For each figure, the original reference period is also indicated, to prevent data generated using different methodologies from being inadvertently mixed.

3. Results

The numbers set the stakes. In 2022, road transport within the EU generated approximately 764 million metric tons of CO2 (carbon dioxide)-equivalent emissions—73.2% of the transport sector’s total emissions and 21.1% of the EU-27’s total emissions. Overall, transportation accounted for approximately 29% of the EU-27’s total emissions that year [1]. The European Green Deal calls for a 55% reduction in CO2 emissions from passenger cars by 2030 and a 90% reduction in emissions from the entire transportation sector by 2050 [2,22]. The car-specific instrument implementing this trajectory has itself proven adjustable: in December 2025, the European Commission proposed amending the 2035 target for new passenger cars from a 100% to a 90% reduction relative to 2021 levels, with the remaining 10% compensable through low-carbon steel or renewable fuels, thereby allowing plug-in hybrids and other partially electrified vehicles to remain on the market beyond 2035 [26]. As of this writing, the proposal has not yet been adopted by the European Parliament and the Council. Based on current trends, emissions from road transport could fall to approximately 596 million metric tons by 2030 and approximately 340 million metric tons by 2050—representing reductions of 22.0% and 55.4%, respectively, compared to the 2022 base year [1]. Whether this projected decrease will withstand the test of actual policy implementation is, of course, a separate question.

From a technical standpoint, the number of low-emission zones has grown rapidly—by about 40% in three years, from 228 (2019) to more than 320 (2022)—and is projected to rise to over 500 by 2025 [24]. London’s ULEZ is the most illustrative case study of whether these systems work in practice. The compliance rate was only 39% when the expansion was announced in 2017. This rose to 86.9% before the rules took effect and to 94.4% one year later. Following the subsequent extension to Outer London, the rate stabilized at around 90% [25]. This is not a negligible improvement, but rather virtually full compliance, a conclusion corroborated by independent air-quality monitoring across low-emission zones in Germany, which found measurable, if modest, reductions in nitrogen oxide concentrations following implementation [27].

Most of these regulatory systems combine a fee with some form of transitional compensation. London imposes a daily fee of 12.50 pounds on non-compliant vehicles, while also offering a scrappage incentive of up to 2,000 pounds [25]; similar combinations are found in other European systems as well. One would expect such a direct financial burden to result in a loss of votes. For the most part, this did not happen. Across three British elections, media coverage of the expansion of the zones had only a modest and inconsistent effect on party preferences—and at the level of individual owners of non-compliant vehicles, there was no statistically detectable effect at all [25]. Politically speaking, therefore, this issue proved far less explosive than the headlines about the daily charge suggested.

Meanwhile, the number of climate lawsuits continues to rise, both in terms of volume and the level of courts to which they are brought. By the end of 2024, a total of 2,967 such cases had been filed in nearly sixty jurisdictions, 226 of them in that year alone, and more than 80% of them are classified as strategic litigation [9]. Moreover, these cases do not remain at the lower court level: the KlimaSeniorinnen case reached the Grand Chamber, and the supreme courts of Germany and the Netherlands have already recognized the existence of positive obligations [11,12,18,19]. The bar is thus constantly rising.

Table 1 summarizes these indicators and evaluates the three most used green mobility measures based on the four-part proportionality test.

Looking through the table: the requirements of legitimate aim and suitability are easily met for all three measures, given the environmental indicators and compliance levels described above. Necessity and strict proportionality, however, pose a greater challenge, and these depend not on aggregate figures but on the design of the regulations. Low-emission zones and congestion charges that leave alternative routes or compliance options open perform better than blunt, one-size-fits-all measures—a fixed deadline for phasing out internal combustion engines, for example, applies to everyone in the same way, regardless of where they live or what kind of vehicle they drive, and it is precisely this uniformity that poses the problem. This distinction is consistent with empirical equity research on congestion pricing, which finds that the perceived fairness of a charge depends heavily on how the revenue is used and whether exemptions are available, rather than on the existence of a charge as such [28].

4. Discussion

4.1. Interpreting the Results: Where Do the Models Differ?

The data point to a conclusion that was not fully anticipated at the outset of this research: the constitutional debate is looking in the wrong direction. It focuses too much on freedom of movement, while the bulk of the actual harm is quietly borne by property owners. None of the systems examined treat driving as a standalone right, and the European regulatory framework also protects movement within a given area rather than the use of a specific vehicle—this much is indeed clear. In the author’s view, however, this approach obscures how green mobility measures work in practice: they intervene not in movement, but in ownership. And the numbers cannot be ignored. Road transport continues to account for nearly three-quarters of the transportation sector’s emissions; more than 320 low-emission zones already restrict who can drive where. Taken together, these mobility restrictions affect property rights, economic freedom, and—more indirectly—freedom of movement to such a profound degree that they require a genuine proportionality review, rather than administrative box-checking disguised as constitutional argumentation. Of the three interests at stake, property bears the heaviest burden. Freedom of movement has received almost all the attention, both in case law and in the accompanying scholarly literature. This balance appears reversed.

The high compliance rate in low-emission zones, together with the absence of a consistent political backlash in the British data, points in the same direction: a well-designed restriction need not be disproportionately costly, either economically or politically. The case for measures still in the early stages of implementation is more uncertain—this is particularly true of the phase-out schedule for internal combustion engines, where necessity depends almost exclusively on the length of the transition period and how it is structured. If a ban is imposed suddenly and without warning, it can hardly be justified under the strict standard of proportionality.

A closer look at Table 1, considering the distinction raised in the Introduction, shows that the phase-out schedule for internal combustion engines rests on a weaker foundation than the aggregate compliance figures would suggest. The low-emission zones are backed by actual, jurisdiction-specific compliance data—the ULEZ figures above are actual, observed numbers. The 2035 phase-out deadline, by contrast, is based solely on projections. This is a different kind of evidence, and the literature consistently errs in treating the two the same way: applying the proportionality logic of low-emission zones by analogy to a fixed deadline conflates two structurally distinct tools. In one case—for an appropriate price—noncompliance remains possible. In the other case, once the deadline arrives, there is no option to opt out. This is precisely where the line should be drawn—between restrictions that price a particular activity and those that prohibit it entirely—since only the latter type triggers the stricter necessity threshold, which entails the near-total exclusion of existing property use. Phase-out schedules that lack a gradual, exception-rich structure—a structure that, incidentally, makes low-emission zones defensible—stand on thinner constitutional ground than most of the literature reviewed in the Introduction would acknowledge. This is not merely a matter of legal design: systematic review evidence on the spatial distribution of electric-vehicle emissions, air pollution, and health benefits shows that an undifferentiated shift to electrification can itself generate new distributional inequities unless the transition is accompanied by targeted support for those least able to adapt [29]. Indeed, the European Commission’s own December 2025 proposal to replace the fixed 2035 target with a graduated 90% reduction, compensable through low-carbon steel and renewable-fuel credits, moves the instrument itself toward precisely the kind of gradual, exception-rich structure this study identifies as constitutionally more defensible [26]—though, as noted above, the proposal remains subject to adoption by the co-legislators.

The application of the principle of proportionality also varies significantly depending on where it is examined. German and Dutch courts have gone so far as to impose mandatory mitigation obligations directly on their own legislatures [18,19]. Strasbourg took a more restrained approach in the KlimaSeniorinnen case—leaving the choice of measures to the state, under the supervision of the Committee of Ministers [11]. This contrast speaks volumes. The German court examined a single identifiable legislative provision and was able to determine with relative precision how an inadequate emissions framework shifts the burden onto future generations [18]. The ECtHR, by contrast, examined the conduct of a Contracting State based on the Convention’s principle of subsidiarity—from a position where the adoption of a similarly specific provision was not actually available and presumably would not have been appropriate. This is best understood not so much as a difference in judicial decisiveness, but rather because of the structural position of the respective courts: a domestic constitutional court reviewing its own legislation can simply demand more than a supranational court reviewing dozens of legal systems at once. The German model, therefore, offers stronger, immediately enforceable protection; the Swiss case, on the other hand, shows that supranational justice—no matter how great its impact may be—leaves the state with significantly greater leeway. Data from the United Kingdom point in a completely different direction: resistance to mobility restrictions tends to be expressed through elections and administrative channels, rather than in the courts [25]. The same standard, different enforcement mechanisms: here, constitutional review; there, supranational oversight; and elsewhere, the voting booth.

As courts increasingly recognize positive climate protection obligations—the KlimaSeniorinnen case being a flagship example—and as the number of climate lawsuits continues to rise, the “legitimate aim” component of the proportionality test is being placed on an increasingly solid foundation [9,11,12]. Governments are expected to build on this and move forward: toward stricter bans on internal combustion engines, broader congestion pricing, and digital emissions monitoring. This is not mere speculation, and each of these measures will raise its own constitutional issues—once again concerning economic freedom, but this time also data protection—issues that will require precisely the type of proportionality analysis applied in this study.

4.2. Constitutional Law Issues in Hungary

Hungary deserves separate treatment, as it is one of the five systems examined, and the situation there is genuinely unsettled. The Fundamental Law protects freedom of movement in wording similar to Article 2 of the Fourth Additional Protocol (Article XXVII), guarantees property rights under Article XIII, and goes further than most systems by recognizing the right to a healthy environment (Article XXI), as well as the state’s constitutional obligation to preserve natural resources for future generations (Article P) [23]. According to Article I, paragraph (3), any restriction on these rights must be strictly necessary and proportionate—a standard that, on paper at least, is as strict as that of Germany or the ECtHR. On 4 June 2025, the Hungarian Constitutional Court struck down a fundamental provision of the 2020 Climate Protection Act, ruling that a static, already outdated emissions target does not comply with the state’s ongoing obligations under Articles P, XX, and XXI, and gave the National Assembly until 30 June 2026 to remedy the deficiency [30]. Structurally, this is like the German ruling—both courts found deficiencies in the legislative framework for climate protection due to a failure to protect future generations. There is, however, one difference that is particularly relevant to this study: the Hungarian decision targeted the general mitigation goal, rather than any specific measure restricting mobility. This, therefore, does not directly reveal anything about how the necessity-proportionality test should be applied to a low-emission zone in Hungary or to the phase-out of internal combustion engines. This leaves Hungary, in the author’s view, in a more vulnerable position under constitutional law than Germany or Switzerland with regard to the narrower issue examined by the study: the strict standard exists on paper, and the court has just demonstrated that it is willing to apply it; yet no one—neither the legislature nor the Constitutional Court—has yet applied this standard to an actual driving restriction, a transitional period, or a compensation system that would make London’s ULEZ defensible in practice. Until such a case arises, Hungary’s green mobility restrictions are, in the author’s assessment, the least tested of the five systems examined in the study.

There is also a second, largely overlooked aspect: the issue of equal treatment. Article XV guarantees equality before the law and prohibits unjustified discrimination, including discrimination based on social or economic status. It should be stressed that geographic location or the age of a vehicle does not constitute a protected characteristic under Hungarian equality doctrine. What is argued here is narrower in scope, but nonetheless valid: green mobility restrictions that disproportionately affect rural residents, lower-income individuals, or owners of older vehicles—without any mitigating mechanism such as London’s scrappage incentive program—raise an equity issue that the necessity-proportionality test alone cannot resolve. Two vehicle owners may be subject to the same rule, yet bear a different burden in practice, depending on their income and whether they have an alternative. When Article I(3) is read in conjunction with Articles XIII, XV, XXI, and XXVII, Hungary has a richer set of legal tools for evaluating green mobility restrictions than has been recognized so far in either domestic or comparative legal literature.

4.3. Toward a Constitutional Framework for Green Mobility

Stepping back from the specific details of individual cases, a pattern emerges: the proportionality review of green mobility measures in all the jurisdictions examined follows a recurring set of regulatory characteristics, rather than a single, uniformly applied doctrinal test. It is worth giving this pattern a name. A five-part constitutional framework for green mobility is proposed below, serving partly as a checklist for legislators drafting such measures and partly as a tool for courts to determine whether a given restriction is likely to withstand a proportionality review.

(1) Legitimate environmental objective. The measure must serve a specific and scientifically sound objective, not a symbolic gesture disguised as policy. The decision by the Hungarian Constitutional Court, which rejected an outdated emissions target, clearly illustrates what happens when this requirement is not met [30].

(2) Technological feasibility. Compliance must be achievable with the technology and infrastructure available. The increase in ULEZ coverage from 39% to 94.4% over a relatively short period of time is the strongest evidence that this is achievable [25].

(3) A reasonable transition period. Those affected need genuine, advance time to prepare. Without it, the “restriction” is just a ban in disguise.

(4) Compensation mechanism. If the fee payment is combined with a scrappage bonus or similar subsidy—following the London model—the economic burden on non-compliant owners is reduced to such an extent that it substantially strengthens the proportionality argument [25].

(5) Availability of alternatives. A restriction that leaves open a realistic alternative route or mode of transportation is much easier to justify than a uniformly applied, fixed deadline, regardless of whether the person concerned has other options. This problem is most acute in rural areas [16,17].

None of the three measures examined meets all five criteria equally well. The phase-out schedule for internal combustion engines is particularly weak regarding the third and fifth criteria; low-emission zones, on the other hand, meet all five criteria well. Framed in this way, the question of proportionality ceases to be binary—constitutional or unconstitutional—and becomes a matter of degree, where each criterion precisely indicates where a given measure is vulnerable. This reformulation points to something narrower than the right to drive, yet more substantial than a mere regulatory gesture: the derivative right to reasonable mobility, developed further in the Conclusions.

5. Conclusions

Is there a constitutional right to drive? In all the systems examined, the answer is no. No jurisdiction treats driving as a fundamental right. Freedom of movement protects mobility within a given territory—not the use of a specific vehicle. Driving remains a regulated activity which, just like anything else the state permits on public roads, is subject to licensing and technical restrictions.

However, this does not settle the matter. Mobility restrictions continue to affect property rights, economic freedom, and—less directly—mobility itself; therefore, their constitutionality can never simply be taken for granted. They must be justified on a case-by-case basis through proportionality arguments. Road transport continues to account for nearly 29% of the EU’s total emissions. This is a large figure, yet its constitutional significance is more often overestimated than is warranted. High emissions justify intervention; however, they do not justify every conceivable form of intervention, and the spread of low-emission zones, as well as increasing compliance, shows that intervention does not necessarily mean a ban. The absence of significant political backlash, together with transition periods and compensation mechanisms, means that well-designed restrictions meet the requirements of necessity and strict proportionality without making life impossible for those affected. Poorly designed measures, as explained in the Discussion, do not.

Taken together, these findings point in a more intriguing direction than a simple “no” answer to the first research question. There is no independent constitutional right to drive a motor vehicle—yet constitutional systems are increasingly recognizing what may be called a derivative right to reasonable mobility. This is not a right to a specific vehicle. Rather, it is a limit on how far the state can go in completely restricting personal mobility without first fulfilling the five conditions set out in the Discussion: a legitimate purpose, technological feasibility, a reasonable transition period, compensation, and the existence of genuine alternatives. It is narrower than the right to drive. It is stricter than the usual administrative discretion. This is the central claim that this study puts forward in contrast to the literature reviewed in the Introduction.

These findings are not merely of theoretical significance. Legislators and local authorities developing low-emission zones, phase-out schedules for internal combustion engines, or congestion pricing systems can use the proportionality assessment presented in the Results to identify those regulatory features—transition periods, technical exemptions, and compensation schemes—that determine whether a measure withstands constitutional review.

The comparative overview presented in the Discussion may also be useful to courts and litigants dealing with climate or mobility disputes when they need to assess how the principle of proportionality is applied differently in various legal systems. Moreover, this framework extends beyond the boundaries of the five jurisdictions examined: anyone planning a similar green mobility measure elsewhere can apply the same analysis to it even before the legislation is adopted, thereby identifying constitutional issues early on rather than in court.

The obvious next step would be to apply the proportionality framework to broader constitutional systems, as well as to instruments not discussed here—such as a more detailed examination of congestion charges and digital emissions monitoring. This would show to what extent the findings can be generalized. The five-part framework proposed in the Discussion, as well as the derivative right to reasonable mobility it underpins, should be regarded as a starting point rather than a closed doctrine. The most necessary next step is to test both in the litigation practice of the coming period.