A Local Authority v X, Y and Z (Permission to Withdraw) is a recent case in a series of cases appearing before the family courts, referred to as the radicalisation cases, which deal with concerns related to extremism, radicalisation and terrorism and their impact on children and families. The radicalisation cases represent a significant legal development and a unique legal moment, facilitating an unprecedented interaction between counterterrorism and family law. The cases pose a number of important and serious legal questions: how should the law, and in particular family law, respond to fears that a child is at risk of childhood radicalisation? How should it deal with the terrorist and/or extremists as a parent? A Local Authority v X, Y and Z is an important radicalisation case which addresses these questions. In this article, I examine how the case deals with two issues: a) childhood radicalisation and its treatment by family law as a separate, free-standing harm which can justify compulsory state intervention and b) the question of parental extremism and/or involvement in terrorist related activity. I claim that although the case includes an important and welcome reaffirmation of the principles of family law in the face of worrying recent developments in the counter-terrorist landscape, this reaffirmation remains fragile, arguing that the case represents a missed opportunity for the family courts to critically reflect on and appraise the nature and purpose of family law's interaction with counter-terrorism.