Constitutional courts operate under a framework of formal and informal rules. While formal rules have been extensively studied, our understanding of informal rules remains limited. Courts often rely on internal practices, traditions and unwritten customs developed over time, posing a significant challenge due to their hidden nature. Numerous constitutional courts lack detailed voting protocols in their statutes and internal regulations, leaving essential aspects to the court's discretion, such as, inter alia, the voting order, deliberation style, outcome versus issue voting and tie-breaking protocols. By employing a case study of strategic breaching of informal voting protocols in the Mexican Supreme Court, this article highlights the complexity of enforcing informal voting rules given that external actors may be unaware of them, along with other factors. Even when informal rules are broadly known, certain circumstances may diminish the efficacy of informal sanctions addressing their breach. Thus, key judicial players, such as chief justices or judge-rapporteurs, may take advantage of the informal rules of voting protocols to advance their policy preferences.