1. The intersection of behavioural science and public and administrative law, with a particular focus on nudge theory as a framework for policy design and implementation

The paper will explore the notion of regulating behaviour in the absence of direct command^[1].

The behavioural sciences (with a particular focus on behavioural economics and behavioural psychology) have yielded a plethora of studies that numerous scholars specializing in public and administrative law have taken a significant interest in. Among the most significant contributions there is the so-called nudge theory, which was skilfully and effectively elaborated by Sunstein and Thaler^[2].

The purpose of this paper is to explore the relationship between the concept of nudging and the action of public authorities. To this end, the following issues will be addressed:

1. an outline of the theory of nudging;
2. the compatibility of the nudge theory and nudge regulation with the legal system;
3. the application of nudge regulation to health and environmental protection;
4. the question of whether nudge regulation constitutes the exercise of power in the legal sense.

2. A concise definition of the concepts of nudge theory and nudge regulation

The theory of nudging is founded on two assumptions: first, that every human decision is made within a specific context (the so-called decision-making context); and second, that individuals, when making choices, exhibit cognitive biases and errors, which systematically result in decisions that are conducive to neither their own interests nor the protection of public interests. Cognitive biases and errors can be defined and typified thanks to the results reached by behavioural sciences. Following this, a decision-making context can be established that nudges individuals to select a particular course of action that aligns with both their personal interests and the broader public interest^[3].

The application of the nudge theory is evident in the nudge regulation concept, which can be defined as the arrangement of the decision-making context. In this sense, nudging may be considered an effective technique for regulating human behaviour, which complements traditional regulation based on rules establishing prohibitions, incentives, controls, and sanctions.

The merits of nudge regulation are indisputable. Individuals retain their autonomy to select the decision-making approach that best aligns with their preferences, thereby evading the influence of the decision-making environment without facing any penalties. In this context, the metaphor of the “navigator”, who provides a route for the motorists but does not oblige them to follow it if they consider an alternative course of action more suitable, is employed in scientific literature. Secondly, the management costs associated with such a regulatory technique are reduced to zero or at least significantly decreased, since there are no binding commands for the individual to follow. Consequently, there is no need to employ public staff to carry out controls. Thirdly, the effectiveness of such a regulatory technique can be measured simply by observing the behaviour of the individuals concerned. Therefore, there is empirical evidence that provides feedback on whether or not the arrangement of decision-making contexts has been successful.

3. The application of nudge regulation to health and environmental protection

Public decision makers may apply nudge regulation in numerous domains. Its usefulness is especially pronounced in the fields of health and environmental protection^[4]. Numerous examples support this assertion. The organisation of canteen menus according to a specific sequence, with the placement of nutritionally advantageous dishes in easily accessible locations, is a strategy employed to influence individual dietary choices. This approach, known as the “framing effect”, can yield favourable outcomes, including enhanced public health and reduced healthcare expenditures, as a consequence of a decline in the prevalence of nutrition-related illnesses.

The implementation of the “duplex” printing option in public administration offices, with no possibility of modification by the individual user, except through a cumbersome and time-consuming procedure, serves to reduce paper consumption with important results in terms of protection of environment. This strategy takes advantage of the “default” effect, leveraging the tendency of users to adopt the most common or default setting.

4. The compatibility of the nudge theory and nudge regulation with the legal system

Sunstein and Thaler propose that nudge regulation is entirely congruent with the legal system, as this regulatory technique does not necessitate any reduction of individual freedom. Since nudging by public authorities does not curtail individual freedoms, its application does not require authorisation by the law.

Overall, nudge regulation is an administrative instrument that, due to its inherent characteristics, can in a natural way complement other known instruments. The only problem is to ensure that this instrument is not misused.

In essence, nudge regulation can be regarded as a form of legal regulation that possesses inherent characteristics, allowing it to be regarded as a natural complement to other established instruments.

Additionally, according in particular to Sunstein, nudge regulation has important virtues that confirm its full compatibility with the legal system, as well as its reliability and effectiveness^[5].

First, nudge regulation is a science-based mode of regulation because it rests on a realistic, scientifically validated assumption about how human beings make decisions. As such, it offers ample guarantee that the decisions of the individuals concerned will conform to those “suggested” by the context architect.

The second virtue lies in the fact that public action based on nudge regulation does not require controls by public authorities because it does not contain binding orders, therefore compliance does not need to be verified and contraventions possibly sanctioned^[6].

Nevertheless, there are authors who express a negative opinion regarding the compatibility of nudging and law. Cserne’s standpoint is of particular significance in this regard^[7]. He asserts an incompatibility between nudge regulation and the legal system, predicated on the premise that the existence of regulation is contingent upon the presence of a justifiable rationale. Nudging regulation contravenes a fundamental tenet of law, namely, the principle that legislation ought to serve as a codified set of guidelines for conduct, substantiated by explicit rationales that are comprehensible to the intended recipients.

It is therefore unsurprising that, given the aforementioned premises, proponents of the incompatibility between nudging and law argue that even where legal provisions exist within the system to permit the use of nudges, these would be considered invalid from a substantive perspective.

5. Nudge regulation as an exercise of power

In addressing the question of the compatibility between nudging and law, it is essential to reject the argumentative strategy employed by Sunstein and Thaler and to reject the assertion that such compatibility merely derives from the preservation of the individuals’ freedom of choice.

This approach effectively diverts attention from the fundamental question of whether the implementation of nudge regulation can be considered an exercise of power^[8].

The topic at hand is of considerable complexity. If, what I believe to be correct, one admits that it is an exercise of power, one must take note that such power has peculiar characteristics compared to the concept of power in the legal sense. In essence, the latter pertains to the establishment of authoritative legal effects within the domain of the recipient. However, a nudge regulation does not yield such an effect because public authorities merely establish the decision-making environment, thereby allowing individuals to retain autonomy in their decision-making processes.

It is evident, then, that the public law scholar is presented with the problem of developing a notion of power other than the traditional one. To this end, reasoning about nudge regulation in terms of power of influence is necessary^[9].

This notion is widely used among social science scholars, such as political scientists, sociologists, and economists, who define power as the intentional influence of others’ actions with concrete possibilities of success. This influence is aimed at directing these actions in a certain direction to achieve a purpose proper to those exercising power^[10].

From this definition, it is easy to grasp the qualifying features of power. For the phenomenon under consideration to occur in reality, the following conditions must be met. First, there must be a subject capable of exercising power in the given context. Second, the subject must decide to exercise power intentionally, transitioning from potential capacity to actual capacity. Third, there must be at least one recipient whose choice or behaviour is to be influenced. Fourth, power must be exercised to achieve a purpose. Fifth, there must be a reasonable probability that the recipient’s behaviour will be influenced in the desired direction. Finally, the person exercising power must possess knowledge of the techniques and methods of exercising power.

A thorough examination of the concept of power in non-legal sciences reveals that the crux of the issue for jurists lies in the absence of an authoritative effect resulting from a nudge regulation. The efficacy of nudge regulation, as an instrument of influence, is a subject of considerable interest.

Consequently, it can be argued that the conceptualization of administrative power within the legal framework is inherently limited in its capacity to encompass instances of influence by one subject on the behaviour of another subject that do not involve the execution of an act with authoritative legal consequences.

It is evident that a significant epistemic deficit exists, impeding the capacity of public law scholars to acknowledge the inherent exercise of power in the legal sense that is intrinsic to nudge regulation. It is therefore necessary to modify the notion of power in the legal sense by extending it to cases in which public authority also exercises a mere power of influence^[11].

It is imperative to acknowledge the existence of power of influence and to recognize the necessity of its reconstruction in terms of authentic legal power. Only through this acknowledgment, the prerequisites and limits of the use of nudge regulation by public authorities may be clearly identified.

In the context of democratic rule of law, all forms of public power – including administrative power – must be grounded in legislation and constrained by the limitations established therein. Consequently, the power of influence, typical of nudge regulation, must be limited by the following constraints.

First, the power of influence must be aimed at the pursuit of public interests. Such a connection exists only in the case where the protection of the public interest comes to depend on individual conduct, in the sense that the latter contributes by neither secondary nor marginal profile to the protection of that interest. This connection thus represents both the prerequisite and the limitation of the exercise of power of influence^[12].

Furthermore, the areas where such hypotheses recur are neither few nor of little importance. The protection of health, which certainly constitutes a public interest, also goes by the fact that individuals assume a healthy lifestyle; the protection of the environment, which is certainly a public interest, also goes by the fact that people assume behaviours consistent with this objective; the protection of the rights of persons in a wheel-chair, which certainly constitutes a public interest of formidable importance and value, requires, in addition to the removal of architectural barriers by the public authorities, the behaviour of third persons not obstructing the passages reserved for them.

Examples are endless, but the ones cited are sufficient to substantiate the legitimacy of the domains in which nudge regulation can appropriately be implemented.

While this constitutes a preliminary step in demonstrating the compatibility of public authorities’ actions with the rule, it is insufficient to pass the “administrative legality” test.

A second issue remains to be addressed: in the absence of a legislative basis that expressly, albeit generally, attributes power of influence to the public authorities, the latter can be exercised only when there is a legislative basis authorizing public power to exercise power understood in the traditional sense, that is, to adopt acts that produce authoritative legal effects vis-à-vis the addressees^[13].

In other terms, the presence of a power of influence can be recognized only in circumstances where the rule of law empowers the public administration to prohibit, command, or encourage a certain behaviour, in accordance with the care of the public interest.

6. Conclusions

The present analysis was guided by the conviction that opposition to phenomena originating from scientific achievements is futile, if not detrimental, when they do not align easily with the conceptual framework of legal discourse. The experience reveals that public administrations act, to a greater extent than one would think, by resorting to the use of the nudge regulation. This results in the preparation of decision-making contexts that, in application of the results arrived at by the behavioural sciences, nudge people to assume a certain behaviour.

Consequently, it is more beneficial to methodically rebuild the phenomenon rather than disregard it or assert its incompatibility with the legal system. This is particularly important because it is indisputable that administrative action through nudge constitutes the exercise of genuine power.

Power does not dissipate from reality through the medium of a linguistic statement containing a negating assertion. Consequently, it is better for the legal scholar try to tame the power of influence.

1. This contribution was presented and discussed by the author at an international conference (Conference 2025 of the Societas Iuris Publici Europaei/SIPE, held in Lisbon in June 2025), with no later revisions or significant additions. Consequently, it is published under the CERIDAP internal review process and without external peer review. It will later be published also in the SIPE Conference Book (Editoriale Scientifica, 2026). ↑
2. See R.H. Thaler, C.R. Sunstein, Nudge. Improving decisions about health, wealth and happiness, New Haven, Yale University Press, 2008 (Italian translation: La spinta gentile. La nuova strategia per migliorare le nostre decisioni su denaro, salute e felicità, Milano, Feltrinelli, 2017). ↑
3. See R.H. Thaler / C.R. Sunstein, La spinta gentile. La nuova strategia per migliorare le nostre decisioni su denaro, salute e felicità, cit., 11. The authors state that the theory is aimed at improving people’s lives. This does not mean, however, that it applies to individual well-being only but also to collective well-being. ↑
4. See M. Cafagno, Integrare la tutela giuridica dell’ambiente con le scienze comportamentali. Un’analisi introduttiva, Torino, Giappichelli, 2025. ↑
5. See C. R. Sunstein, Five Reasons for Choice-Preserving Approaches, in Harvard Law Review Forum, 210, vol. 127, n. 6, 2014, 210-217. ↑
6. See C. R. Sunstein, Five Reasons for Choice-Preserving Approaches, cit., according to which nudge regulation «may well have high benefits without high costs» (211). The author also states that public regulators have «to give careful consideration to choice-preserving approaches, and generally to adopt a (rebuttable) presumption in their favor, at least where no standard market failure is involved» (211). ↑
7. See P. Cserne, Making Sense of Nudging Scepticism: Three Challanges to EU Law’s Learning from Behavioural Sciences, in A. Alemanno, A.-L. Sibony (eds.), Nudge and the Law. A European Perspective, Oxford, Hart publishing, 2015, 279-299. ↑
8. On this specific problem see A. Zito, La nudge regulation nella teoria giuridica dell’agire amministrativo. Presupposti e limiti del suo utilizzo da parte delle pubbliche amministrazioni, Napoli, Editoriale Scientifica, 2021, 85-96. ↑
9. On the concept of power of influence see C. Castelfranchi, The Micro-Macro Constitution of Power, in ProtoSociology, vol. 18/19, 2003, 208-269, who argues that «power is also a fundemental topic in the social siences, in particular in sociological theory (starting from classics like Marx, Pareto, Weber), in political science, in organization sciences, in anthropolgy; but also in economics (negotiation power, position power, theory of oligopolyies and monopolies, etc.)» (208). ↑
10. For this definition of power see, ex multis, A.I. Goldman, Toward a Theory of Social Power, in Philosophical Studies, vol. 23, n. 4, 1972, 221-268; M. Foucault, Le sujet et le pouvoir, in M. Foucault, Dits et écrits II, 1976-1988, Paris, Gallimard, 2001, 1041-1062; P. Morris, Power. A Philosophical Analysis, Manchester, Manchester University Press, 1987; V.G. Ledyaev, Power. A Conceptual Analysis, New York, Nova Science, 1997; M. Brigaglia, Potere. Una rilettura di Michel Foucault, Napoli, Editoriale Scientifica, 2019. ↑
11. See A. Zito, La nudge regulation nella teoria giuridica dell’agire amministrativo. Presupposti e limiti del suo utilizzo da parte delle pubbliche amministrazioni, cit., 95-96. ↑
12. See A. Zito, La nudge regulation nella teoria giuridica dell’agire amministrativo. Presupposti e limiti del suo utilizzo da parte delle pubbliche amministrazioni, cit., 109-110. ↑
13. A. Zito, La nudge regulation nella teoria giuridica dell’agire amministrativo. Presupposti e limiti del suo utilizzo da parte delle pubbliche amministrazioni, cit., 112-113. ↑