Translation:Shulchan Aruch/Choshen Mishpat/4

Paragraph 1
A person may take the law into his own hands in order to safeguard his interests. If he sees something that belongs to him in the hand of another person who robbed it from him, he may take it from his hand and if the latter makes a stand against him, he may strike him until he releases it, (if he can't save the item in another way) (Tur). Even if it is a matter that would not cause a loss if he waits until he takes legal proceedings against him, provided he can prove that what he takes is his own in accordance with the law. Nevertheless, he has no right to seize a pledge for his debt when it matures.