Klingon law was the legal system of the Klingon Empire. The system was built upon the traditions and precedents developed over centuries of Klingon history.

In 2367, when he became the Arbiter of Succession, Captain Jean-Luc Picard stated the Rite of Succession would proceed according to Klingon law. (TNG: "Reunion")

Later that year, Gowron asked what would happen if the House of Duras or its allies attempted to block his installation as Chancellor, Picard stated he would deal with any challenge according to Klingon law. Gowron expressed his doubts with Picard's assertion.

When Picard's authority as arbiter was challenged by Toral, Gowron announced that all who followed Toral were rejecting Klingon law. (TNG: "Redemption")

In 2368, Commander William T. Riker studied Klingon law and ritual after being asked by Worf with the ritual suicide Hegh'bat. (TNG: "Ethics")

According to this system, the fulfillment of a blood oath was considered an act of justice. (DS9: "Blood Oath")