This chapter aims to shed light on migrant Children’ relationship with the Law. As children are supposed to be totally ignorant from a juridical point of view(Aït Ahmed, Gallant, et Meur 2019, Thronson 2006, 2010), Carers, Social workers and most of migrant children themselves think they cannot improve their agency to better defend their rights (Morrow 1999, Crawley 2006, White et al. 2011, Wolff 2019). However, migrant Children have to deal daily with the Law, and have their situation deeply shaped by juridical mechanisms (Senovilla Hernández 2014, Lind 2019). This study shows that, unsurprinsingly, the Law and its procedures may be perceived by migrant Children as oppressive and obscure, and as a consequence they may have become accustomed to circumvent them, to avoid claim, to develop alternative strategies to face obligations (Senovilla Hernández et Bailleul 2016, Bricaud et Thibaudeau 2017, Perrot 2019). Far from being the evidence of the absence of their agency, we argue that these practices are paradigmatic of different kind of migrant Children’ capabilities to get used to an hostile environment (Bumiller 1987,O’Connell Davidson 2011, Thompson et al. 2019), and to face and use its (infrequent) legal opportunities (Ewick et Silbey 2004). This chapter will also underline the ways the Law can become a tool of emancipation and protection for them, by adopting a child-centered approach (UNHCR 2018, Safe Passage 2020, Micreate 2020). This contribution is based on an ethnographic fieldwork at the French-UK Border : numerous interviews have been conducted with minors in transit, and many participant observations have been possible thanks to several years of field experience within a legal access association.