Senators in South Dakota approved a Senate Bill 55 on Wednesday barring schools from prohibiting teachers from questioning established scientific theories. It could be assigned to a South Dakota House committee next week.

“No teacher may be prohibited from helping students understand, analyze, critique, or review in an objective scientific manner the strengths and weaknesses of scientific information presented in courses being taught which are aligned with the content standards established pursuant to,” the 36-word bill reads.

South Dakota Sen. Jeff Monroe sponsored the bill following failed attempts in 2014 and 2015 to give teachers more leeway regarding controversial scientific lessons. In 2014, Monroe sponsored SB 112, which would have stopped school boards from prohibiting teachers from teaching creationism.

Though South Dakota’s SB 55 doesn’t specifically mention evolution, experts say the bill leaves the door open for teachers to teach whatever they want with regards to controversial topics.

“This is horrible, but let’s say I believe in eugenics,” Deb Wolf, a high school science instructional coach told the Argus Leader. “(SB 55) says that I couldn’t be prohibited, I couldn’t be stopped from teaching that as long as I did it in an objective scientific manner, and it doesn’t specify what that means.”

Similar bills are making their way through legislatures in Oklahoma and Indiana. According to the National Center for Science Education, Oklahoma’s SB 393 would require administrators to “assist teachers [in finding] effective ways to present the science curriculum as it addresses scientific controversies.” And Indiana’s Senate Resolution 17 would urge the state department of education “to reinforce support of teachers who choose to teach a diverse curriculum.”

“Where topics are taught that may generate controversy (such as biological evolution), that the curriculum should help students to understand the full range of scientific views that exist, why such topics can generate controversy, and how scientific discoveries can profoundly affect society,” Indiana’s Senate Resolution 17 reads.

Glenn Branch, deputy director of the National Center for Science Education, told the Hill the language of these bills makes them “very hard to challenge on the basis that they’re unconstitutional, because they’re not requiring anyone to do anything.”

“They’re no longer trying to ban teaching evolution,” Branch said. “They’re no longer trying to balance teaching evolution. They’re now trying to belittle evolution.