Precedent (Persuasion (Influence) Mastery) Masterful argument and knowledge of arcane legal history (combined with a little creativity) can convince the magistrate that the Advocate's client should have all charges dropped and be released, though often with a recommendation that they quit the locality. Grants +2 PDL to attempt to sway the court to release the client. There is always a danger the local lord with exercise their privileges and intervene and the often illiterate nobles are less open to convoluted defenses and mistrust cunning words.
Appeal (Persuasion (Influence) Grand Mastery) Through no fault of the Advocate, a case may go against them. While that would be the end of the matter for a lawyer with little prestige or knowledge of the system, a skilled and famous Advocate can prevail upon any court to have the matter heard at a superior jurisdiction. That might be the Church courts, the Imperial court, the disputations in the Universities of Europe, or if necessary there is always appeal to the Pope in Rome! The process could be endless and it creates more time and opportunity to discover new evidence, influence the correct people or if the case is otherwise hopeless it can at least be dragged out in the hope that a new Emperor or Pope may pardon the defendant.