翻案 is a separable verb (离合词) meaning to overturn a verdict or judgment, either in a legal case or in historical evaluation. The verb 翻 and the noun 案 can split: you can insert a measure word, result, or time expression between them, like 翻了一个案 ('overturned a case'). The word has two main applications: in law (reverse a court verdict) and in historiography (re-evaluate a historical figure or event).