Attorney Brian Barnard also pointed out that interracial wedlock once was illegal, but now is lawful. The concept of marriage is changing, he said, and the legal definition should include polygamy.
"The state of Utah should not be able to criminalize the maintenance of an intimate relationship," Barnard argued in a challenge to prohibitions in state law and in the state constitution against bigamy and polygamy.
Assistant Utah Attorney General Jerrold Jensen agreed concepts about wedlock are changing, but added, "The state has always had the authority to regulate marriage."
That authority includes the power to ban incestuous, underage and same-sex marriages, he said.
The lawyers made their arguments to U.S. District Judge Ted Stewart in a hearing on a lawsuit filed by three Utahns who want to live together legally as husband and wife and wife. The trio filed suit in January against Salt Lake County clerks for refusing to issue a marriage license to the man, who already is legally married to one of the women, so he could marry the second woman.
The three contend the ban on plural marriage violates their constitutional rights to practice their religion and to free association. In addition, they say the law unfairly targets religious polygamy because people who create multiple common-law marriages through cohabitation are never prosecuted for bigamy.
At Tuesday's hearing, Barnard asked the judge to find the anti-bigamy and anti-polygamy laws unconstitutional based on a ruling last year by the U.S. Supreme Court. That ruling struck down a Texas law banning sodomy between same-sex couples. In Lawrence v. Texas, the court held that the law violated the privacy rights of consenting adults.
In this case, there are two consenting adults, Barnard said - including one who is married to another woman - who want to engage in intimate relations and be free of the stigma of being criminals because they are polygamists.
He added that a man in Utah could impregnate six girlfriends without facing criminal charges, while another who lives with six wives and takes responsibility for his children could be prosecuted.
Jensen told Stewart that laws against polygamy are enforced fairly and apply to everyone who practices plural marriage, even for non-religious reasons. He also said that the case involves private conduct between consenting adults, not state-sanctioned marriage.
The judge took the arguments under consideration and said he would rule later.