You know the laws and procedures to handle a variety of civil matters. Country disputes, foreign rights, tax law, contracts, property, you've learned it all at the highest levels. You know the criminal code and are aware of legal tensions between countries. You also know police procedure as it relates to the case and are familiar with the politics of the courts.
At the highest levels, you're fit to be a judge (but likely need Politics to back you up.) You will have penalties for working with laws not of your home (unless the GM decides you've had enough time to acclimatize.)