A more thorough explanation:

Definition: In Scots law, a criminal letter is a summons.

Example: If a person is suspected of committing a crime in Scotland, the prosecutor may issue a criminal letter to summon them to court.

Explanation: A criminal letter is a legal document that orders a person to appear in court to face criminal charges. It is similar to a summons in other legal systems. The example illustrates how a criminal letter is used in Scotland to initiate criminal proceedings against a suspect.