noun
appellant
Legal term for a party who appeals a court decision to a higher court.
控訴人は判決を不服として上級裁判所に控訴した。
The appellant, dissatisfied with the ruling, appealed to a higher court.
A party who appeals to the Supreme Court (final appeal), whereas 控訴人 appeals to a high court (first appeal).
Compound of 控訴 (appeal) + 人 (person). The term is a straightforward legal coinage.