Homo Sacer is a concept from ancient Roman law that refers to a person who is excluded from legal protection. This individual can be killed without consequence, but cannot be sacrificed in a religious context. The term highlights the tension between law and life, illustrating how certain individuals can be rendered outside the bounds of society. The idea was later explored by philosopher Giorgio Agamben in his book "Homo Sacer: Sovereign Power and Bare Life." Agamben uses the term to discuss how modern states can designate individuals as outside the law, raising questions about sovereignty, human rights, and the nature of citizenship.