NASHVILLE, Tenn. (AP) — Tennessee, where the nation's first big legal battle over evolution was fought nearly 90 years ago, is close to enacting a law that critics deride as the "monkey bill" for once again attacking the scientific theory.

The measure passed by the Tennessee General Assembly would protect teachers who allow students to criticize evolution and other scientific theories, such as global warming. Republican Gov. Bill Haslam said this week he would likely sign it into law.

Haslam said the State Board of Education has told him the measure won't affect the state's current scientific curriculum for primary, middle or high school students. Louisiana enacted a similar law in 2008.

"I think the one thing about that bill is this: Nothing about the curriculum of the state of Tennessee will change, and the scientific standards won't change," he said. "So I think some of the discussion about its impact has probably been overblown."

The bill says it would encourage critical thinking by protecting teachers from discipline if they help students critique "scientific weaknesses."

Scientists in Tennessee and the American Association for the Advancement of Science are asking Haslam to veto the bill, saying that evolution is established science that shouldn't be taught as a controversy.

"The Tennessee legislature is doing the unbelievable: attempting to roll the clock back to 1925 by attempting to insert religious beliefs in the teaching of science," three Tennessee scientists wrote in an op-ed column in The Tennessean.

The three writers hold doctorate degrees and are members of the National Academy of Sciences: Roger D. Cone and Jon Kaas of Vanderbilt University and Robert G. Webster of St. Jude Children's Research Hospital. They argue that the law is unnecessary and likely to provide expensive legal fights and hurt the economy in Tennessee, which is home to Oak Ridge National Laboratory.

The Tennessee Education Association called the bill a distraction from the most pressing education issues in the state.

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"I think at a time when we're trying to put a focus on science, math, education; to pass something like this really sends a signal that the state is going backward instead of forward," TEA lobbyist Jerry Winters said. " ... They're avoiding the real problems in education by dealing with some of these emotional hot-button issues."

The state held the famous Scopes "monkey trial" in 1925 in Dayton, Tenn., and opponents of the legislation say evolution is still under attack in 2012.

School teacher John Scopes was convicted of violating state statute by teaching evolution in biology class and fined him $100. The Tennessee Supreme Court overturned it on a technicality a year later. In 1967, Tennessee's anti-evolution law was revoked.

Some believe the bill could open the door for religious teaching in the classroom. The American Civil Liberties Union of Tennessee asked the governor to veto it.

State ACLU executive director Hedy Weinberg said allowing students to critique "scientific weaknesses" is language frequently used by those seeking to introduce non-scientific ideas like creationism and intelligent design into science curriculum.

"No one doubts the value of critical thinking to any serious course of scientific study, but this legislation is not truly aimed at developing students' critical thinking skills," she wrote.

House sponsor Bill Dunn, a Knoxville Republican, said the proposal states that it is "not ... construed to promote religion."

"What the bill says is that as long as you stick to objective scientific facts, then you can bring that into play," the Knoxville Republican said. "So if students start asking questions or if there's debate on it, it's not a one-sided debate. But it is a fair debate, in that it's objective scientific facts that are brought forward."