For a citation issued by a county sheriff, can the sheriff's department conceal the identity of the complainant from the individual cited?
Jurisdiction: a Montana county Justice Court. Citation: misdemeanor offense (non-violent) of a state law.
What if the complainant is a minor?
Can a minor be a complainant? Does an adult need to be a co-complainant?
A complainant isn't a legal status. Criminal proceedings are filed in the name of "the People" or in the case of an ordinance violation, of the government bringing the charges.
The government must disclose the witnesses against a criminal defendant whose testimony will be presented at trial (often this can be demanded prior to trial, but the disclosure requirements can be more lax for the minor offenses tried before a justice of the peace). This requirement is constitutional and flows from what is known as the "Confrontation Clause" in the 6th Amendment to the U.S. Constitution as incorporated against state and local governments through the due process clause of the 14th Amendment.
But the complaining party need not always be a witness.
In certain kinds of cases, such as juvenile offense, the defendant and sometimes some witnesses aren't disclosed to the public, but are known to the defendant and the defendant's counsel.
The prosecutor also has to disclose (sometimes only upon request), any exculpatory evidence in the possession of the prosecutor and law enforcement involved in the case. This is called a Brady obligation after the U.S. Supreme Court case establishing it. But it wouldn't be particularly uncommon for a complaining party to be neither a witness nor someone who could be a source of exculpatory evidence.
Justice of the Peace proceedings in Montana aren't brought on the basis of grand jury indictments (which in Montana are used only very sparingly in felony cases where it is useful to the prosecution to use them, rather than all felony cases). But grand jury testimony is generally top secret, and generally must only be disclosed to a defendant when an informant's testimony will be used at trial. Often proof of a case at trial is tailored so that a confidential informant's grand jury testimony (which is often the effective source of the complaint initiating a criminal investigation) is not disclosed, by not relying on that testimony.
