A closer look at both positions reveals a fundamental conflict that is also significant for the upcoming revision of the State Treaty on Gambling: To what extent does the existing scientific evidence hold—and to what extent must the potential effects of protective measures on channeling and provider choice be taken into account?
What the Bremen Policy Paper Calls For—The Path to Proactive Protection
Researchers Tobias Hayer, Britta Jacobsen, and Jens Kalke evaluated a total of 42 scholarly publications. These include findings on 48 individual player protection measures from areas such as player exclusion, personalized feedback, limit systems, pop-up messages, responsible gambling tools, advertising restrictions, telephone interventions, and self-assessments. From this, the authors derive eight recommendations for prevention practices. The research project was funded by the Federal Ministry of Health.
The recommendations include, among other things, centralized player exclusion systems for offerings with moderate and high addiction potential. The authors generally assess limit systems as suitable for counteracting gambling-related addiction risks. In their view, financial limits should be mandatorily prescribed, and their specific design should be regularly reviewed from a scientific perspective.
The authors also believe that pop-up messages should be included in social prevention strategies as a preventive tool. However, the policy paper itself acknowledges that only minor positive effects can be expected from such interventions at this time. The paper reaches a similar conclusion regarding motivational telephone interventions but nevertheless recommends that they be made mandatory in social and prevention strategies.
In doing so, the policy paper provides a comprehensive overview of the current state of research and, at the same time, offers clear impetus for more proactive player protection.
The methodological question: What happens once a limit is reached?
This is precisely where Dr. Bastian Scholz’s criticism comes in. He points out that none of the 48 measures has been supported by the strongest scientific evidence to date. Furthermore, many studies have limitations regarding study design, observation period, or the generalizability of the results. The policy paper itself highlights these limitations.
Of particular interest is the discussion surrounding the monthly deposit limit of 1,000 euros in Germany, which applies across all providers and forms of gambling.
The study by Auer and Griffiths, evaluated in the policy paper, reveals a striking discrepancy: Objective gambling behavior data showed that 7.6 percent of the players surveyed had reached the limit at least once. In the survey, however, 60.5 percent stated that they had already reached the limit. Of this group, 42.5 percent reported that they subsequently continued gambling with other providers, either online or offline.
These data do not prove a shift toward the illegal market. However, they highlight a key difficulty in evaluating player protection measures: A change in gambling behavior within an observed account does not automatically reveal how a person’s overall gambling behavior is evolving. Scholz sums up this objection with the following statement: “An effect within an account is not necessarily an effect in the market.” He therefore calls for examining not only the impact of an intervention at an individual provider but also possible shifts to other accounts, forms of gambling, or unauthorized offerings.
Spain and the Question of Advertising’s Impact
Another point of contention concerns advertising restrictions. The policy paper itself notes that, to date, only one concrete scientific study exists on the impact of such restrictions on gambling behavior.
The 2025 study by Aonso-Diego, García-Pérez, and Krotter from 2025 focuses on Spanish regulations. Among other measures, the study examined time limits on radio, television, and video advertising, as well as bans on the use of celebrities, sports sponsorship, and certain customer acquisition strategies. The study found, among other things, declines in the number of newly opened gambling accounts and in betting volumes.
The authors of the policy paper consider the results promising but explicitly call for further pilot projects and evaluation studies. The University of Bremen also states in its press release that advertising restrictions should be viewed as a promising approach and that their effects in Germany should be further investigated.
Scholz, on the other hand, criticizes the fact that the developments in Spain cannot be reduced to a single advertising measure. Since several regulatory changes interacted, it is not straightforward to determine which individual measure was responsible for which observed effect. He also points out that the Spanish Supreme Court repealed parts of the regulatory package there in 2024.
Considering Player Protection and Channeling Together
The academic debate highlights a crucial question for the evaluation of the State Treaty on Gaming. Player protection measures must be assessed based on whether they actually reduce risky or problematic gambling. At the same time, in addition to player and youth protection, the State Treaty on Gambling also aims to channel demand toward legal offerings and curb illegal gambling.
Precisely for this reason, when evaluating individual measures, it is not sufficient to consider only changes within a single gambling account. Equally relevant is the question of whether players reduce their overall gambling behavior, switch to other legal offerings, or turn to unauthorized offerings.
The policy paper by the University of Bremen and ISD provides a comprehensive overview of the current state of research on this topic while also identifying numerous existing research gaps. Criticism from the gambling industry, in turn, makes it clear that when drawing policy conclusions, policymakers must consider not only the immediate effects of protective measures but also their potential impact on the overall market.
The evaluation must combine both perspectives
The crucial question for the further development of the State Treaty on Gambling is therefore likely not so much whether player protection is necessary, but rather which measures have been proven to be effective and what impact they have on overall gambling behavior.
Scientific findings on bans, limits, pop-ups, or interventions form an important basis for this. Equally important, however, is a comprehensive examination of potential diversion and displacement effects.
A robust evaluation of the State Treaty on Gaming should therefore not pit player protection against market channeling. The two go hand in hand: protective measures can only be fully effective if as large a portion as possible of gambling activity takes place within the regulated and controllable market.