South Dakota Codified Laws
Chapter 15 - Record And Exhibits
Section 15-15-8 - Letter size paper required in all courts.

15-15-8. Letter size paper required in all courts.
Eight and one-half inch by eleven inch paper size shall be the only accepted size in all of the courts of the State of South Dakota. This section shall be applicable to all documents except original documents filed as exhibits.

Source: Supreme Court Rule 82-3.