Minn. R. Juv. P. 22.03
Subdivision 1. Service and Filing. The child's counsel or the prosecuting attorney may serve on the other parties and file with the court administrator a notice to remove the judge assigned to a trial or hearing. The notice shall be served and filed within seven (7) days after the child's counsel or the prosecuting attorney receives written notice, or oral notice in court on the record, of which judge is to preside at the trial or hearing but, in any event, not later than the commencement of the trial or the hearing.
Subd. 2. Removal of Presiding Judge. No notice shall be effective against a judge who has already presided at the trial, probable cause hearing, or other evidentiary hearing of which the party had notice, except where a party shows cause why a judge should be removed. After a party has once disqualified a presiding judge as a matter of right, that party may disqualify the substitute judge only upon an affirmative showing of cause.
Minn. R. Juv. P. 22.03