In the March of Peest ruled by a Coalition, a character must undergo a Trial by combat.
He has been framed by A cult or brotherhood - bound by a mission and code - and if found guilty of Murder, his punishment will be Baleful Polymorph. The prisoner permanently changes into a small animal. One of my favourite D&D modules is Castle Amber. Wouldn’t it be a neat twist for the central garden to be the prison of several banished beings changed into the form of small animals? If the subjects fail their second saving throw, they even gain animal intelligence, in effect becoming just another creature in the garden.

March - Similar to a county, but usually a borderland, ruled over by a marquis. Usually heavily fortified due to it's strategically important position.
Coalition - A coalition government, in a parliamentary system, is a government composed of a coalition of parties. A coalition of parties is also an electoral fusion. The union of different political parties or groups for a particular purpose, usually for a limited time.
Trial by combat - Fight to the death, winner is innocent