Koster’s comments Thursday come a day after St. Louis officials issued marriage licenses to four same-sex couples.
Koster said he is seeking an injunction preventing St. Louis officials from issuing marriage licenses to same-sex couples because local officials should not be acting in conflict with state laws.
Missouri voters approved a constitutional amendment in 2004 limiting marriage to only one man and one woman.
Koster is a Democrat who is running for governor in 2016. He said in a written statement that many people have changed their minds about marriage in the past decade but that it is his duty as attorney general to defend Missouri’s laws.
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