Caput lupinum (transl. wolf's head) or caput gerat lupinum (transl. may he wear a wolfish head) are terms used in the English legal system and its derivatives. The terms were used in Medieval England to designate a person pronounced by the authorities to be a dangerous criminal, who could thus be killed without penalty.

The Latin term caput lupinum literally means "wolf's head" or "wolfish head", and refers to a person considered to be an outlaw, as in, e.g., the phrase caput gerat lupinum ("may he wear a wolfish head" / "may his be a wolf's head"). Black's Law Dictionary, 8th edition reads "an outlawed felon considered a pariah – a lone wolf – open to attack by anyone."^[1]

Caput lupinum or caput gerat lupinum are used in the English legal system and its derivatives.^[2] The terms were used in Medieval England to designate a person pronounced by the authorities to be a dangerous criminal whose rights had been waived, who could thus be legally harmed or killed without penalty by any citizen.^[3]

The term caput lupinum is first recorded in the text Leges Edwardi Confessoris as a law attributed to the 11th century ruler Edward the Confessor. This law stated that a man who refused to answer a summons from the king's justice for a criminal trial would be condemned as a Caput lupinum.^[4]

The thirteenth-century writer on law, Henry de Bracton, wrote in his book De Legibus et Consuetudinibus Angliae that outlaws "gerunt caput lupinum"- "bear the wolf's head." Bracton added that this meant that outlaws could thus be killed without judicial inquiry.^[5]

The fourteenth-century English legal textbook The Mirror of Justices stated that anyone who was accused of a felony, who refused three times to attend county courts, would be declared Caput lupinum or "Wolfshead". The book added ""Wolfshead!" shall be cried against him, for that a wolf is a beast hated of all folk; and from that time forward it is lawful for anyone to slay him like a wolf." ^[3]