Countermeasures are an established mechanism in International Law that allows a State to respond to the unlawful actions of another. This tool enables the injured State to act in a way that would otherwise be illegal, with the objective of compelling the breaching State to cease its violations. Similarly, the concept of belligerent reprisals refers to a similar mechanism in International Humanitarian Law (IHL), which allows a State to violate IHL rules in response to the previous violations of another State in order to enforce compliance. It has been a part of armed conflicts throughout history, and its codification can be traced back to the earliest iterations of IHL. Over time, the scope and permissibility of reprisals have become significantly more constrained. Today, their regulation is primarily governed by customary International Humanitarian Law (CIHL), which draws upon the International Committee of the Red Cross (ICRC) Customary Rules and established case law. This article will examine the exact legal boundaries of belligerent reprisals and evaluate the practice.