This concluding Chapter demonstrates that legal responses to foreign fighters at the international, European, and domestic levels have been robust yet generally inconsistent with the rule of law and human rights. Throughout Europe’s legal response to foreign fighters, four fundamental challenges have emerged which have prevented states and international organisations from resolving the foreign fighter conundrum in accordance with the rule of law and human rights. Firstly, the Chapter argues that framing the foreign fighter conundrum has proved to be a real definitional quagmire, caused primarily by the introduction of the novel concept of the ‘foreign terrorist fighter’ into international law. Secondly, attempts by the United Nations, the European Union, and the Council of Europe to resolve the foreign fighter conundrum through multilateral channels have by and large been inconsistent with the rule of law and human rights. Thirdly, the Chapter argues that approaching the foreign fighter conundrum almost exclusively through the lens of counter-terrorism does not reflect the complexity of the multi-faceted threat posed by foreign fighters and has exacerbated the conflation between counter-terrorism law and international humanitarian lawInternational humanitarian law, to the detriment of the latter. Fourthly, at all three levels legal responses to foreign fighters have focused primarily on pre-emptingPre-empting future acts of terrorism. This trend has sharpened the preventive turnPreventive turn that counter-terrorism law has taken across the globe in the aftermath of 9/11, at the expense of the rule of law and human rights.