District Court (First District) Unlawful cohabitation register of action book, 1890-1891.

This series contains one register of action book maintained by the Territorial First District Court that focuses exclusively on unlawful cohabitation cases that appeared before the court. Charges of unlawful cohabitation by the federal attorneys came with the crackdown on polygamy in the Utah Territory in the late 19th century. Suspected polygamists were charged under the Edmunds Act, also known as the Edmunds Anti-Polygamy Act of 1882. The Edmunds Act was a United States federal statute signed into law on March 23, 1882 by president Chester A. Arthur, declaring polygamy a felony. The act not only reinforced the earlier 1862 Morrill Anti-Bigamy Act but also revoked polygamists' right to vote, made them ineligible for jury service, and prohibited them from holding political office.

The cases in this book range from 1889 to 1891. The information recorded in this register book includes a register case number, the names of plaintiff (always the United States) and defendant(s), theattorney for the plaintiff (always the U.S. District Attorney), and the dates and proceedings of all actions taken in a case.