This paper aims at showing the reality of law, or “law in action”, far from a legal belief that takes regulations as a guarantee for effectiveness. Law in action has to take into account a range of mediation and devices to assure its implementation. To prove this, we will focus on the research that analyzes the mobilizations of a Catalan association of gay and lesbian families (FLG) in the context of same sex marriages in Spain and the institutionalization of same sex couples in Catalonia. We will pay attention to the actions and situations in which law is referred, and these range from mobilization to the implementation of law.