Ancient Greek laws consist of the laws and legal institutions of ancient Greece.

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

While some of its older forms can be studied in the Gortyn code, its influence can be traced in legal documents preserved in Egyptian papyri and it may be recognized at a later period as a consistent whole in its ultimate relations to Roman law in the eastern provinces of the Roman Empire, with scholars in the discipline of comparative law comparing Greek law with both Roman law and the primitive institutions of the Germanic nations.

Diversity of Greek law Ancient Greece lacked a codified law code used across the country. Ancient Greece was not a state but existed as a collection of city-states known as poleis (πόλεις), all with different laws. However, numerous ideals within the various laws of the city-states were rooted in the same context, notably, cultural unity.  Ancient Greek culture advanced their own religion and language, along with various customs that were rooted in religion and tradition. From Greek culture, common bases in law emerged : δίκη ("law, justice"), κύριος ("lord, master"), βλάβη ("injury"), among other concepts. With the general discontinuity in law between the various city-states, Athens is typically the model provided for Greek law.

Historical sources There is no systematic collection of ancient Greek laws; the earliest notions of the subject can be found in Homeric poems. Later, the works of Theophrastus, On the Laws, are said to have included a recapitulation of the laws of various barbaric as well as of the ancient Grecian states, yet only a few fragments of this work remain.

Athens Incidental illustrations of the Athenian law are found in the Laws of Plato, who describes it without exercising an influence on its actual practice. Aristotle criticized Plato's Laws in his Politics, in which he 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 the mechanics of the law courts, and thus enables historians to dispense with the second-hand testimony of grammarians and scholiasts who derived their information from that treatise.

Other evidence for ancient Athenian law comes from statements made in the extant speeches of the Attic orators, and from surviving inscriptions.

Procedural laws Athens Historians consider the Ancient Athenian law broadly procedural and concerned with the administration of justice rather than substantive. Athenian laws are typically written in the form where if an offense is committed, then the offender will be punished according to said law, thus they are more concerned with the legal actions which should be undertaken by the prosecutor, rather than strictly defining which acts are prosecutable. Often, this would have resulted in juries having to decide whether the offense said to have been committed was in fact a violation of the law in question.

Development of ancient Greek laws The earliest Greek law to survive is the Dreros inscription, a seventh century BC law concerning the role of the kosmos. This and other early laws (such as those which survive in only fragmentary form from Tiryns) are primarily concerned not with regulating people's behavior, but with regulating the power of officials within the community. These laws were probably set up by the elites in order to control the distribution of power among themselves.

Athens One of the earliest dateable legal events in Athenian history is the creation of the Draconian law code by Draco, 620 BC.. However, the homicide law is the only one known due to it surviving the Solonian reforms. The law seems to have distinguished between premeditated and involuntary homicide, and provided for the reconciliation of the killer with the family of the dead man.. The homicide law of Draco was still in force in the fourth century. Though the rest of the code is unknown, it was by Athenian tradition known to have been very harsh.

The Athenian law codes set forth by Draco were completely reformed by Solon, who was the archon of Athens 593 BC. Solon's reforms included reforms to land ownership and the cancellation of debts and the abolition of slavery for those who were born Athenian. Yet, attributing specific legal innovations and reforms to Solon and his successors is notoriously difficult because there was a tendency in ancient Athens to ascribe laws to Solon irrespective of the date of enactment.

Sparta Though Athens is commonly cited in discussions about Greek law, Sparta also developed a lasting legal code, attributed early on to Lycurgus. Though there is controversy about the existence of Lycurgus, the first written record of Lycurgus as the Spartan lawgiver is attributed to Herodotus in the 5th century BCE. Lycurgus' biographer was Plutarch, who wrote the Life of Lycurgus in the 1st century CE. Plutarch's work mentions that Lycurgus likely introduced the Spartans to the works of Homer, along with establishing law practices following his ventures to Crete, Asia, and Egypt. Notably, Lycurgus established two bodies in Spartan law: the gerousia and the apella. The gerousia was known as the council of elders and included the two kings, likely preparing documents concerning business ventures for the apella. The gerousia also held significant power over the judicial system in Sparta, especially in the case of the death penalty. The apella on the other hand closely mirrored the ekklesia existing in other Greek polis. The apella was the citizen-body consisting of men over the age of 30, and they voted on the proposals submitted by the gerousia. They also had the power to elect those who served on the gerousia, discussed matters of foreign policy, and helped determine succession and military powers.

Other ancient Greek cities In other city-states, there were also notable lawgivers. In Thebes, Philolaus of Corinth published the first law code of this city. In another notable city-state, Corinth, Pheidon composed the first set of the city laws. Though the author of the law code of Megara remains unknown, it is likely a law code existed promoting Athenian-like democracy within the city-state.Courts and judicial system Along with the official enforcement of the law in the courts in the Grecian states, justice and social cohesion were collectively enforced by society at large, with informal collective justice often being targeted at elite offenders.

Courts in Athens Ancient Greek courts were cheap and run by laypeople. Court officials were paid little, if anything, and most trials were completed within a day, with private cases done even quicker. There were no court officials, no lawyers, and no official judges. A normal case consisted of two litigants, arguing if an unlawful act had been committed. The jury would decide whether the accused was guilty, and should he be guilty, what the punishment will be. In Athenian courts, the jury tended to be made of the common people, whereas litigants were mostly from the elites of society..

In the Athenian legal system, the courts have been seen as a system for settling disputes and resolving arguments, rather than enforcing a coherent system of rules, rights and obligations. The Prytaneion court was responsible for trying unknown people, animals, and inanimate objects for homicide, and it is assumed that it was in order to ensure that Athens was free of blood-guilt for the crime.

The Athenian court system was dominated by men. The jury was all-male, and it has been argued that the Athenian court seemed to have been remarkably unwilling to allow any female presence in the civic space of the lawcourt itself.

Athenian law and the role of Areopagus Athenian law is largely a ‘balancing mechanism’ between the interests of the rich and the poor. As such, principles of equality took centre stage in political and legal developments. It was these principles that shaped the institutional design, which, in turn, shaped the socioeconomic structure of Athens. Importantly, the principles of equality and fairness would be invoked to keep the powers of the executive and legislative bodies from becoming tyrannical.

The Council of Areopagus served as a dispute resolution method between private citizens. But it also “kept watch over the magistrates to see that they executed their offices in accordance with the laws”. As suggested by E. Carawan, the Council held public officials accountable for their wrongdoings in office – implying the existence of proto-administrative law. The Council acted as the “guardian of the laws” in Athens. What exactly this role entailed is unknown. Some have proposed that, by being the guardian of the laws, the Council had the power to overrule the assembly for an undesirable or unconstitutional resolution. Others have suggested that this guardianship is a ‘convenient summary’ of the powers possessed by the Council. P.J. Rhodes qualifies the latter view by adding that the Council used its ex-archon makeup to justify new ways of enforcing the law. From a reading of Aristotle’s ‘Constitution of the Athenians’, consensus is that the idea of guardianship of the laws is associated with the power of the Council to check and balance the executive powers of the magistrates, because the text directly associates guardianship with ‘keeping watch’ over the magistrates in office.

The doctrines of graphe paranomon and graphe nomon me epitedeion theinai provided the basis for which decrees from executive bodies and legislation respectively could be challenged for their compatibility with existing laws. The purpose of this doctrine is to “advise for the good of the state” and for every citizen to “express their opinion”, which falls squarely within the democratic rights associated with Athenian citizenship. Scholars have identified 3 ways that this doctrine operated in practice: (i) procedural violations in enacting legislation, (ii) legislation contravening specific provisions and (iii) legislation contravening the basic principles that can be logically deduced from legislation. The importance attached to the different avenues has been the subject of debate, with some scholars arguing that legislation was often challenged if it violated basic principles of existing legislation, while others argued that speeches made in courts heavily emphasised procedural or substantive contraventions. A. Lanni offered that, while speeches did capture and show an appreciation towards the basic principles derived from existing legislation, the basic principles themselves seemed to reinforce the decisions made by the legislature as opposed to recognising substantive sociomoral values.