The judge presiding at the trial may not testify in that trial as a witness. No objection need be made in order to preserve the point.
Committee Comment - 1977
The rule as provided states the general rule in Minnesota as well as the approach generally followed in the United States. State v. Sandquist, 146 Minn. 322, 178 N.W. 883 (1920). See also Annot., 157 A.L.R. 315 (1945).