The talion principle is the belief that criminals should be punished by being treated in a reflection of a suffering of their victim. For example, if a criminal wounded their victim's eye, their eye should also be wounded. This principle is also known under its Latin name lex talonis.

It is first seen in ancient Babylonian law, and is also found in the Bible (in the famous formulation in Exodus as "an eye for an eye, a tooth for a tooth"), and in early Roman law (from which the names lex talonis and talion principle are derived.)

However, later both Roman and Jewish law progressively softened and then rejected the practice. Today it is considered a violation of human rights ("cruel and unusual punishment" to use the terminology of the US Constitution), although it still has been practiced under extremist regimes such as the Taliban.