The constitutional amendment created by Referendum 1 has been effectively nullified since June 26, 2015, when the United States Supreme Court ruled in Obergefell v. Hodges that state-level bans on same-sex marriage are unconstitutional.

A legal status identical or substantially similar to that of marriage for unmarried individuals shall not be valid or recognized in this state.

The legislative history of the amendment is as follows: The amendment, which took effect on November 7, 2006, constitutionally banned same-sex marriages, which were never recognized by the state and was statutorily banned since 1979, and civil unions or civil union equivalents, which were never recognized by the state.

Domestic partnerships in Wisconsin, legal statewide for state employees only and 1 county and 3 municipalities at the time, were unaffected by the amendment.

In April 2009 the Wisconsin Supreme Court was asked in McConkey v. Van Hollen to rule on whether the 2006 Referendum 1 was constitutional.