A civil union is a legally recognized relationship between members of a same-sex couple, with rights similar to those of a marriage relationship.
As of my knowledge cutoff in 2023, Utah does not recognize civil unions. In 2004, Utah passed Amendment 3, which amended the state constitution to define marriage as exclusively between a man and a woman, effectively banning same-sex marriages and any legal union that is substantially equivalent to marriage, which would include civil unions. However, following the U.S. Supreme Court decision in Obergefell v. Hodges in 2015, same-sex marriage became legal across the United States, including in Utah. This ruling granted same-sex couples the right to marry and thereby receive the same legal benefits and protections as opposite-sex married couples. As a result, same-sex couples in Utah can choose to marry but do not have the option of entering into a civil union.