North Dakota's Legislature is encouraging disrespect for the law by making it illegal for a man and woman to live together without being married, a legislator says.

If North Dakota prosecutors began enforcing the anti-cohabitation law, which provides a 30-day jail term and a $1,000 fine, the state would need a "$10 billion prison," Sen. Tracy Potter, D-Bismarck, said Wednesday.

"We're saying that we have optional laws, laws that we don't really mean," Potter said during a Senate Judiciary Committee hearing on the repeal measure. "We shouldn't have laws like that."

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Tom Freier, a spokesman for the North Dakota Family Alliance, said repealing the measure would signal that the state doesn't value marriage and the societal benefits it brings.

"If we look at the research, social science evidence suggests that living together is not a good way to prepare for marriage, or to avoid divorce," Freier said. "Cohabitating is not positive for the family, and poses a special risk for women and children."

North Dakota is one of the few states that outlaws cohabitation, which is defined as a man and woman living together "openly and notoriously" as if they were married.

It is listed as a sex crime in state law, alongside adultery and incest. There are few records of a cohabitation case being prosecuted, aside from a North Dakota Supreme Court appeal in the 1930s.

Attempts to repeal the anti-cohabitation law have failed in the last two sessions of the Legislature. Two years ago, a repeal bill was defeated in the North Dakota House.