RICHMOND — Under an old law, it’s illegal in Virginia for unmarried couples to live together. Now, a state senator and delegate are trying to wipe it off the books.

A law dating to the late 19th-century makes it a misdemeanor for “any persons, not married to each other, [to] lewdly and lasciviously associate and cohabit together.”

Probably no one has been prosecuted under the law for decades, but state officials used it as recently as the early 1990s to threaten revocation of a daycare provider’s state license, said Sen. Adam Ebbin (D-Alexandria), who has brought the bill with Del Scott Surovell (D-Fairfax). The measure comes before a Senate committee Monday.

“It’s an 1877 law. I think it’s time to revise that,” said Darlene K. Davis, 73, of Norfolk, who nearly lost her daycare license after a state inspector learned she and her boyfriend of 16 years lived together.

“She said, ‘You live in sin,’” Davis said.

The state backed down nine months after the American Civil Liberties Union filed a lawsuit on her behalf, Davis said.

“I learned of it last year and thought that it is not only unnecessary but bizarre that Virginia would still have on its book a law essentially outlawing consenting adults from living together,” Ebbin said. “It’s obviously an outdated vestige from a very different time.”

Ebbin said only three other states still have cohabitation laws on the books: Mississippi, Michigan and Florida.

The law also prohibits anyone, married or not, from engaging in “open and gross lewdness,” meaning sex acts in public. That aspect of the law would still stand.

Several members of the Senate Committee on Courts of Justice, which will hear the bill Monday morning, declined to comment, saying they were unfamiliar with the measure.

“[W]e haven’t taken a position on this,” Chris Freund, spokesman for the conservative Family Foundation of Virginia, said via email. “We’re just monitoring it.”