New formal legal regulations are introduced to promote gender equality and to combat discrimination in the legal system. However informal social rules, which are commonly based on patriarchal hierarchical norms, still persist within all institutions. By comparing the aims of new formal rules to their final effects, it can be seen that the results achieved through their application are directly dependent on their informal contexts. The aim of the article is to reveal the informally embedded formality that exists within the Polish legal system. By this I refer to the roles played by informally and culturally embedded formal rules when new rules are introduced within an existing context. The specific context for my analysis is the introduction and implementation of new formal rules based on EU equity law. Specifically, the analysis identifies and discusses the factors arising from the Polish informal institutional context that influence the way the anti-discrimination law is applied.