Complex sentence: Between 1996 and 2004,39 states passed laws and constitutional amendments that defined marriage as consisting solely of different-sex couples, most of which also explicitly prohibited the state from honoring same-sex marriages performed in other states and countries.
Split into simpler sentences: Between 1996 and 2004,39 states passed laws and constitutional amendments that defined marriage as consisting solely of different-sex couples. Most also explicitly prohibited the state from honoring same-sex marriages performed in other states and countries.