The Rental Enforcement Game: Tenant Protection, Screening Strategies, and the Evolution of Impersonal Exchange

This conceptual working paper reconstructs housing regulation as a sequential rental-enforcement game involving prospective tenants, housing providers, public administrations, and intermediaries. Its central hypothesis is conditional: when expected enforceability declines and no credible public guarantee replaces it, providers may withdraw units, demand stronger credentials, delegate screening, or prefer applicants supported by personal networks. Protection for incumbent tenants may then impose an entry penalty on outsiders. The paper distinguishes two evolutionary levels. Under the author's legal extended phenotype framework, transmissible legal information is expressed immediately in legislation, while administrative routines and market responses are downstream effects. Evolutionary game theory is used to specify strategies whose prevalence may change through learning, imitation, entry, and exit. It also proposes the concept of a defensive legal phenotype for preambles that anticipate constitutional, parliamentary, and reputational attack. Spain's Royal Decree-Law 26/2026 supplies the motivating case, with Argentina's post-2023 rental reform used only as a limited comparative observation. The contribution is a falsifiable research program rather than a constitutional opinion or causal estimate. It specifies competing mechanisms and observable implications for supply, screening, public-payment performance, network reliance, and the transmission of defensive legislative language.