It has been 20 years since the Supreme Court invalidated sodomy laws with its decision in Lawrence v. Texas, but legal codes inherited from colonial laws and used to prosecute L.G.B.T.Q. people by banning some sexual acts remain in place across the country.

Efforts to remove the laws in 12 states have taken on a new urgency after another landmark Supreme Court ruling.

Justice Clarence Thomas said in his concurring opinion last year in Dobbs v. Jackson Women’s Health Organization — the decision that overturned the constitutional right to an abortion in Roe v. Wade — that previous Supreme Court rulings affirming the right to privacy should be reconsidered.

And though the sodomy laws were made null, there was no mandate for states to update their legal codes, leaving those dormant laws as potential restrictions if the Supreme Court revisits the ruling.

Gregory R. Nevins, a lawyer at Lambda Legal, the L.G.B.T.Q. advocacy group that won the Lawrence v. Texas case, said the Dobbs decision “raises the urgency level” for getting the sodomy laws off the books.

“And probably for some states means that they’ll be reluctant to repeal it,” Mr. Nevins said. “As we saw, there were a lot of old abortion laws on the books that got dusted off after Dobbs.”

Maryland and Minnesota repealed their remaining sodomy laws this year, but such laws still exist in Florida, Georgia, Kansas, Kentucky, Louisiana, Massachusetts, Michigan, Mississippi, North Carolina, Oklahoma, South Carolina and Texas.

If the Lawrence v. Texas decision from June 2003 were overturned, the state-level sodomy laws could be revived “as long as it appears the right to privacy is under threat from a conservative court,” said Wesley Phelps, the author of “Before Lawrence v. Texas: The Making of a Queer Social Movement.”

The state laws were inherited from British common law, which considered sodomy a sexual act that would not lead to procreation and banned it, Mr. Phelps, who is also an associate professor at the University of North Texas, said.

Acts forbidden for such reasons could include intercourse between people of the same sex, oral and anal sex between a man and a woman and masturbation. The legal language is not always explicit and it changes state by state. In North Carolina, for example, the sodomy law makes it a felony to commit a “crime against nature, with mankind or beast.”

Over time, the language defining a “crime against nature” changed in some states, oftentimes more clearly targeting same-sex couples. Other states decided that the legal system was moving toward preserving the right to privacy and repealed sodomy laws to reflect that, like Illinois did in 1961.

In the states where the sodomy laws have remained, though, they have been used as tools of oppression and discrimination against gay and lesbian people, Mr. Phelps said.

In Texas, he said, people who wanted to apply for certain jobs or professional licenses, such as those needed for medicine or cosmetology, would have to sign a document vowing to follow the state’s laws. This meant that, before Lawrence v. Texas, gay and lesbian people either had to perjure themselves or not apply.

“It wasn’t really a criminal issue for gays and lesbians; it was an issue of discrimination,” Mr. Phelps said.

Today, even though the laws are not enforceable, they can still be used to discriminate or, erroneously, to arrest people, leading some state lawmakers to try to repeal them.

In March, the Maryland legislature repealed a provision that made it illegal to perform oral sex or to participate in sexual acts that were deemed “unnatural or perverted” with a human or an animal. Gov. Wes Moore, a Democrat, did not veto the repeal bill, allowing it to become effective without his signature in May. The clause will be struck from the state’s criminal code on Oct. 1.

Maryland had repealed a more explicit sodomy ban in 2020, but the “unnatural or perverted” language that remained was used in May 2021 to arrest four gay men during a raid on an adult book and video store.

Also in May, Gov. Tim Walz of Minnesota, a Democrat, signed a public safety bill repealing the state’s sodomy ban as well as bans on adultery and fornication. The Minnesota Supreme Court had ruled that the sodomy ban was unconstitutional in 2001.

Lawmakers in Texas have tried to repeal the sodomy law that the Supreme Court struck down in Lawrence v. Texas every year since the case was decided in 2003. This year, the legislative session ended before the House had time to consider repeal legislation.

In Massachusetts, a bill moving through the State Legislature would erase several instances of out-of-date language, including sodomy laws that criminalize “unnatural and lascivious” acts. The so-called archaic-laws bill would also strike out words such as “common night walkers” and “common street walkers” from state law and replace them with “persons.”

State Representative Jay Livingstone, a Democrat, is the co-filer of the archaic-laws bill in the House and said that these efforts had become more important following recent Supreme Court decisions.

“Massachusetts has made a number of statements in favor of L.G.B.T.Q. people, but we still have the laws on our books to prohibit what people would generally consider lawful activity between consenting adults that have been used in the past to target the L.G.B.T.Q. community,” Mr. Livingstone said. “We should repeal those prohibitions to reflect the values that we want in our society.”