Feudal Law and Order
Generally the lord or lady of the realm is both the judge and jury for most criminal matters in a feudal realm.
The monarch can demand jurisdiction over any legal issues over any of his vassals though most prefer to let their vassals handle their own legal issues and only step in when there is a legal issue that concerns more than one fief.
If the crime is severe, the presiding feudal lord may offer the case to his or her liege as polite formality in which case their lord will usually give his blessing that he believes the vassal is wise and just enough to be able to handle it.
Social class is a huge determiner of sentencing. Murder is nearly always considered a serious crime but a noble convicted of killing a commoner will likely have to pay a large fine while a commoner convicted of killing a noble is almost certainly going to be executed.
Nobles, even kings and queens are not above the law. This is the theory if not always the practice. Some realms qualify as constitutional monarchies where even the king is subject to legal limits. A common limitation is that kings are the ultimate interpreter of laws but they cannot simply create new laws on a whim. Even if there isn't a constitutional limit on a monarch, monarchs are often constrained by unwritten custom and tradition.
A king who is consistently unjust and flouting traditions can expect to have his vassals withhold their aid, if not worse.
Also, the priesthoods are very concerned with justice, and there are at least nine different views on justice emanating from the various priesthoods. Generally speaking, Masks, Guardians, Keepers, and Lanterns are the most likely to make their opinions on legal rulings known but in theory any priesthood could get involved if they see an injustice.
If a secular ruler is truly acting as if the law does not apply to him, one or several priesthoods can step in and either silently back a coup, or outright remove a sinful ruler. Often even a vague insinuation of the possibility of this is enough to cause a tyrannical ruler to ease up a bit.
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