A religious group that believes God literally created the world has brought a legal action against a biology professor, claiming that he refuses to write letters of recommendation for students who do not believe in evolution.
It represents yet another dispute in the American education system about the teaching of the biblical version of creation in science classes.
The action has been filed against Professor Michael Dini of Texas Tech University in Dallas by a student and the religious group, the Liberty Legal Institute. The institute argues that Prof Dini is discriminating against students on the grounds of belief and has asked the department of justice to investigate.
Kelly Shackelford, chief counsel for the institute said: "Students are being denied recommendations not because of their competence in understanding evolution, but solely because of their personal religious beliefs."
The issue was first raised last year when a complaint was made and the university defended Prof Dini.
"A letter of recommendation is a personal matter between a professor and student and is not subject to the university control or regulation," Texas Tech's Chancellor, David Smith, said at the time.
No one was available for comment at the university yesterday.
Prof Dini refers callers to a website that explains his position. The site advises students seeking a recommendation to be prepared to answer the question: "How do you think the human species originated?"
"If you cannot affirm a scientific answer to this question, then you should not seek my recommendation for admittance to further education in the biomedical sciences," Prof Dini writes.
At the centre of the legal complaint is the Texas Tech student Micah Spradling, 22, who left the university and moved to Lubbock Christian University because of Prof Dini's policy.
Mr Spradling said that he did not believe in evolution and could not say that he did. He has now re-enrolled at Texas Tech. "You read about it [evolution] in textbooks. I could explain the process, maybe how some people say it happens, but I could not have said ... I believe in it."
A creationist website, creationism.org, argues: "Each new false religion of the post-Flood period has sought to detract from our Creator and from our responsibilities in this life; evolution's effect is no different. Pray about this!"