A Tennessee measure that criticsamong them leading scientists, as well as science teacherssay will undermine the teaching of evolution in public schools is set to become law, though Republican Gov. Bill Haslam declined to sign the legislation.

Approved by lopsided votes in the Republican-controlled House and Senate, the bill would protect teachers who discuss with students the "scientific strengths and scientific weaknesses" of existing theories, such as on evolution and global warming.

Haslam made clear his misgivings about the legislation, even while he stopped short of issuing a veto.

The Republican governor said that while he doesn't think the bill changes scientific standards or the state's science curriculum, he also believes that "good legislation should bring clarity and not confusion," the Associated Press reports.

"My concern is that this bill has not met this objective," he said. "For that reason, I will not sign the bill but will allow it to become law without my signature."

Proponents say the legislation is aimed at fostering "critical thinking" in the classroom. Republican Sen. Bo Watson, the leading Senate sponsor, charged that any confusion about the legislation's purpose "comes from the opponents of the bill, who have mischaracterized a lot of what the law would actually do," according to a story in the Chattanooga Times Free Press.

But the bill has come under fire from a variety of organizations, including the American Association for the Advancement of Science, the Tennessee Science Teachers Association, and the National Association of Biology Teachers.

Three prominent scientists from Tennessee, all members of the National Academy of Sciences, wrote a letter published in the Tennessean newspaper that derided the legislation as "misleading, unnecessary, likely to provoke unnecessary and divisive legal proceedings." Harkening back to the Scopes trial of 1925, they said, "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."

Watson told the Times Free Press that he hopes the legislation will lead to more student interest in science.

"Perhaps if science classes allow for less rote memorization and student regurgitation and more discussion, students might get excited about science and understand that it's not just about memorizing facts and data," he said, "that actually there is debate and conversation that occurs in the science class."

But Eugenie C. Scott, the executive director of the National Center for Science Education, said that "telling students that evolution and climate change are scientifically controversial is miseducating them. Good science teachers know that. But the Tennessee legislature has now made it significantly harder to ensure that science is taught responsibly in the state's public schools."