On 8 march 2011, the grand chamber of the european court of justice issued a significant ruling regarding the interpretation and scope of the concept of european union citizenship. In an eagerly anticipated judgment, the court held that article 20 of the treaty on the functioning of the european union (“tfeu”) confers a right of residence and a right to obtain a work permit upon the parents of a minor dependent european union citizen who has never left the member state of his or her nationality. The ruling is notable for having redefined the “internal situation” rule and extended the reach of the primary law provisions on union citizenship beyond directive 2004/38/ec. Yet, some of the potential implications of zambrano have been qualified by the court's subsequent rulings in mccarthy and dereci. In those cases, the court restricted the scope for eu citizens who have never exercised their free movement rights to rely on eu law in order to derive rights of residence for their third-country-national family members in their country of nationality. Moreover, the brevity of the zambrano judgment indicates substantial disagreement amongst the judges and has the effect of leaving a number of issues unclear. What are the precise limitations to relying on article 20 tfeu in a situation that falls outside the scope of article 2004/38/ec? how does the ruling impact the ongoing discussions on reverse discrimination and the protection of fundamental rights in the e.u.? after briefly describing the factual and legal background of the case, the opinion of advocate general sharpston, and the court's judgment, we will discuss the questions raised above before considering the potential implications of the ruling for member states' migration and nationality laws.