By definition, biometrics consists of sensitive data about the individual. Therefore, the State must ensure a higher degree of safeguarding measures in all phases of handling such data. This article argues that data-subjects whose biometrics are gathered for identification are protected through the right to biometric private life under international human rights law at all times. Furthermore, the law of armed conflict also contains relevant provisions. The European Convention on Human Rights provides detailed rules for the protection of biometric private life, subject to limitations and possibly derogations. This protection covers the whole data life cycle of collection, retention and disclosure of biometrics. Two points are of importance here when assessing what is permissible: (1) The original purpose for which biometric data collection was initiated remains decisive. (2) The use of special measures such as limitations or derogations, does not permit States to annihilate the protection of a person’s biometric private life. The right to biometric private life remains protected during armed conflict, because international human rights law and the law of armed conflict re-enforce each other. Therefore, armed forces must: (1) define in detail for what purpose biometric data is collected, retained and disclosed, and (2) maintain strict adherence to the originally intended usage of the biometric data and refrain from any divergence therefrom. This article argues that the legal framework under international human rights law in general and the European Convention on Human Rights in particular, is sufficiently flexible to balance the interests of the rights holder with those of the State or the community at large. Nevertheless, this flexibility makes it harder to predict the outcomes of a legal assessment, and a case-by-case approach must therefore be expected.