The Assizes were the primary local courts of criminal trial in Ireland. The assize system consisted of justices travelling the country to try both civil and criminal cases. While they can be traced back to the 13^th and 14^th centuries it was after the Flight of the Earls (1607) that the system extended throughout the country. By 1614 five assize circuits had been established. The judges of the superior courts were required to travel these circuits as justices of assize holding an assize for each county. By 1695 every county was visited twice yearly in spring and summer.

As well as their legal functions the assizes also fulfilled social, economic and political roles. By 1850 much of the existing civil business had been transferred to the quarter sessions .

Following independence the assizes were replaced by circuit courts which are essentially similar to the assizes.