AFAIK, these "John Doe" laws are particular to Wisconsin, and are over 100 years old.
Here's a link to the statute.
History:
Legal proceedings: What is a John Doe investigation anyway?The John Doe proceeding is an institution sanctioned by long usage since Wisconsin’s territorial days.1 The provisions of Wis. Stat. section 968.26 currently define the scope of a John Doe proceeding in Wisconsin, which is intended as an independent, investigatory tool to ascertain whether a crime has been committed and if so, by whom.
The goal is to allow the judge to determine whether it appears probable from the testimony given that a crime has been committed, and whether to file a complaint. But the proceedings are also designed to protect innocent citizens from the fallout of frivolous prosecutions.2
As the Wisconsin Supreme Court stated in 1889: “When [the John Doe] statute was first enacted the common-law practice was for the magistrate to issue the warrant on a complaint of mere suspicion, and he was protected in doing so. This was found to be a very unsafe practice. Many arrests were made on groundless suspicion, when the accused were innocent of the crime and there was no testimony whatever against them. This statute was made to protect citizens from arrest and imprisonment on frivolous and groundless suspicion.”3 Unlike normal criminal proceedings, which can be initiated if there is probable cause to believe a person has violated the law, John Doe proceedings help law enforcement develop the evidence necessary to establish the very existence of probable cause. The John Doe proceeding gives law enforcement powers not otherwise available to them. For example, it gives law enforcement the power to subpoena witnesses, to take testimony under oath, to offer immunity from prosecution, and to compel the testimony of reluctant witnesses.
The proceeding is overseen by a circuit court judge. It is the responsibility of the John Doe judge to use his or her training in constitutional and criminal law and in courtroom procedure in determining the need to subpoena witnesses requested by the district attorney, in presiding at the examination of witnesses, and in determining probable cause.
In short, it is the judge’s responsibility to ensure procedural fairness and to decide whether to issue a complaint (that is, a criminal charge).
Thanks for looking that up. That’s a nasty law.
“In short, it is the judge’s responsibility to ensure procedural fairness and to decide whether to issue a complaint (that is, a criminal charge).”
And we look to Judge Kukla, that paragon of virtue, to see to it that “procedural fairness” is preserved. She should be brought up on charges and removed from office.