A character letter to a judge should establish your credibility, paint a full picture of the defendant and be respectful, among other things. A character letter is designed to show support for a defendant in a criminal case.These letters have the potential to influence the court. How To Start Your Letter. The character reference letter for court serves the purpose of offering the Judge insights into the Defendant's moral or mental attributes. What parents and witnesses need to know about character reference letters to the court for child custody. Includes a downloadable sample and template. Introduce yourself in the opening paragraph.