noun
first trial; first instance
Legal term for the initial court hearing or trial in a multi-tier judicial system. Often contrasted with 二審 (second instance) and 最高裁 (Supreme Court).
一審で無罪判決が出たが、検察は控訴した。
A not-guilty verdict was handed down at the first trial, but the prosecution appealed.
この事件は一審から最高裁まで争われ
This case was fought from the first instance all the way to the Supreme Court.