How did city-states in ancient Greece use international arbitration?

In ancient Greece, international arbitration served as a vital mechanism for resolving disputes between independent city-states without resorting to war. When diplomatic negotiations failed, states would agree to refer their controversies to a neutral third party—often a commission or another state—whose binding decision, or award, settled the matter.123

These disputes frequently concerned territorial boundaries, a common source of friction between neighboring poleis. For example, when a territorial disagreement arose between Epidaurus and Corinth around 240 BCE, the Achaean League appointed a commission of 151 Megarians to mediate, and their formal report has been preserved.4

Records of these proceedings were often inscribed on stone or metal and displayed at major pan-Hellenic sanctuaries like Delphi or Olympia. Beyond boundary issues, arbitration was sometimes integrated into formal peace treaties, such as the Thirty Years' Peace between Athens and Sparta, which included a commitment to renounce armed attacks if the opposing party agreed to submit to arbitration.45