reversal of a guilty verdict; acquittal on appeal
Legal term for overturning a conviction, typically through an appeal or retrial, resulting in a not-guilty verdict.
They won a reversal of the guilty verdict at the appellate court.
As a result of the retrial, the acquittal on appeal became final.
無罪 simply means 'not guilty' or 'innocence', while 逆転無罪 specifically refers to the overturning of a previous guilty verdict.
逆転勝訴 is a broader term for a reversal resulting in a win in any civil or criminal case, not limited to acquittal.
Compound of 逆転 (reversal) and 無罪 (innocence, not guilty). The term is a straightforward legal expression with no obscure historical derivation.