Heliaia (Greek: ἡλιαία): the supreme lawcourt of classical Athens.
Established in the first half of the sixth century BCE by Solon as an appeal court, the Athenian Heliaia took over several responsibilities from the Areopagus in the course of the fifth century. The jury, which gathered in a building in the southwestern corner of the agora, consisted ot 501, 1001, or 1501 members, chosen by lot from among 6,000 citizens over the age of 30. (The large number of heliasts made bribing impossible.) Pericles introduced a juror's fee (one obol per day) in order to allow the poorer citizens to exercise this democratic right. According to Aristophanes' play The Wasps, staged in 422, Cleon had increased this pay to three obols.
A lawsuit conisted of an oath, a set of speeches by the prosecutor and the accused; in a secret ballot without debate, the jury had to decide whether the accused was guilty. If the jury decided that the accused was guilty, there were two speeches and a second vote about the punishment. For example, Socrates was found guilty by 280 against 220, and received the capital punishment by a vote of 360 against 140.
Because the Heliaia originalle was a court of appeal, it was impossible to appeal against a verdict. The necessity to defend oneself - lawyers did not exist in Greece - was an incentive for professional speech writers. If less than a hundred jurors decided that the accused was guilty, the persecutors were convicted and had to pay the trial costs, which could be quite substantial.