I thought you might. :) The medieval legal precedent involves a royal daughter accusing her father's murderer in front of the assembled princes. Wilhelmine, as a princess of two electorate princely houses (Brandenburg and Hannover) and a direct blood relation to the dead victim, himself a prince of said houses, would be entitled to bring her suit in front of the Emperor, who has to hear her out in full. (And in public.) And we know from the memoirs she had a way with words if she wanted to. And the theatrical instinct of an opera composer. Imagine all the anachronistic Verdi soundtrack you want. (He wrote some mighty vengeance tunes, after all!)