In 2018, Switzerland adopted a new gambling law. Prevention is based on two mechanisms: the operator’s pre-existing obligation to detect and exclude those most at risk, and the obligation for the cantons to implement a prevention tax based on gaming income. The field of gambling in Switzerland has complex regulations, with a federal and cantonal institutional network, of public and private law. The main players include operators, regulators, other state services (including finance, police, health), prevention and treatment, players and beneficiaries of the income generated. A model for assessing the impact of this new law should include as results indicators the degree of suicidality, over-indebtedness, quality of life for players and their families, as well as social costs. The means indicators should cover prevention by operators, prevention external to operators and places of help and care. Process indicators should include the health and social situation of problem gamblers, the knowledge of the public and professionals, as well as the share of problem gamblers in revenue derived from games.