Ancient Greek law is a branch of comparative jurisprudence relating to the laws and legal institutions of Ancient Greece.

Greek Iuris law has been partially compared with Roman law, and has been incidentally illustrated with the aid of the primitive institutions of the Germanic nations. It may now be studied in its earlier stages in the laws of Gortyn; its influence may be traced in legal documents preserved in Egyptian papyri; and it may be recognized as a consistent whole in its ultimate relations to Roman law in the eastern provinces of the Roman empire.

The existence of certain panhellenic principles of law is implied by the custom of settling a difference between two Greek states, or between members of a single state, by resorting to external arbitration. The general unity of Greek law is mainly to be seen in the laws of inheritance and adoption, in laws of commerce and contract, and in the publicity uniformly given to legal agreements.

No systematic collection of Greek laws has come down to us. Our knowledge of some of the earliest notions of the subject is derived from the Homeric poems. For the details of Attic law we have to depend on ex parte statements in the speeches of the Attic orators, and we are sometimes able to check those statements by the trustworthy, but often imperfect, aid of inscriptions. Incidental illustrations of the laws of Athens may be found in the Laws of Plato, who deals with the theory of the subject without exercising any influence on actual practice. The Laws of Plato are criticized in the Politics of Aristotle, who, besides discussing laws in their relation to constitutions, reviews the work of certain early Greek lawgivers. The treatise on the Constitution of Athens includes an account of the jurisdiction of the various public officials and of the machinery of the law courts, and thus enables us to dispense with the second-hand testimony of grammarians and scholiasts who derived their information from that treatise. The works of Theophrastus On the Laws, which included a recapitulation of the laws of various barbaric as well as Grecian states, are now represented by only a few fragments (Nos. 97-106, ed. Wimmer).