The need to protect the rights and freedoms of migrants, as enshrined in international principles and obligations, is a red line that must not be crossed in the management of migration by States, regardless of whether the law provides for criminal sanctions for violations of immigration law or allows migrants to be deported to their countries of origin rather than detained. The different types of immigration detention under European and national law are associated with a hybrid collection of misleading labels (detention, treatment, etc.) that conceal the instruments used to deprive people of their freedom. While, on the one hand, European and international law allows for the deprivation of liberty to control immigration, on the other, migrants’ guarantees and rights are at risk of vulnus. This is because coercion and the question of whether liberty should be deprived or merely restricted is the vexata quaestio faced by conventional and European law, the parameters and criteria of which it is yet to clearly and uniformly define, though deprivation of liberty in some form or other is gradually increasing. The various migrant detention measures present criminal law scholars with the challenge of reshaping the conventional and constitutional limits of criminal law with regard to procedures that essentially amount to hidden punishments, but whose preventive character is the inevitable criterion for the legitimacy of criminal sanctions.