UBBOCK, Tex., Feb. 2 — A biology professor who insists that his students accept the tenets of human evolution has found himself the subject of Justice Department scrutiny.
Prompted by a complaint from the Liberty Legal Institute, a group of Christian lawyers, the department is investigating whether Michael L. Dini, an associate professor of biology at Texas Tech University here, discriminated against students on the basis of religion when he posted a demand on his Web site that students wanting a letter of recommendation for postgraduate studies "truthfully and forthrightly affirm a scientific answer" to the question of how the human species originated.
"The central, unifying principle of biology is the theory of evolution," Dr. Dini wrote. "How can someone who does not accept the most important theory in biology expect to properly practice in a field that is so heavily based on biology?"
That was enough for the lawyers' group, based in Plano, a Dallas suburb, to file a complaint on behalf of a 22-year-old Texas Tech student, Micah Spradling.
Mr. Spradling said he sat in on two sessions of Dr. Dini's introductory biology class and shortly afterward noticed the guidelines on the professor's Web site (www2.tltc.ttu.edu/dini/Personal/letters.htm).
Mr. Spradling said that given the professor's position, there was "no way" he would have enrolled in Dr. Dini's class or asked him for a recommendation to medical school.
"That would be denying my faith as a Christian," said Mr. Spradling, a junior raised in Lubbock who plans to study prosthetics and orthotics at the University of Texas Southwestern Medical Center in Dallas. "They've taken prayer out of schools and the Ten Commandments out of courtrooms, so I thought I had an opportunity to make a difference."
In an interview in his office, Dr. Dini pointed to a computer screen full of e-mail messages and said he felt besieged.
"The policy is not meant in any way to be discriminatory toward anyone's beliefs, but instead to ensure that people who I recommend to a medical school or a professional school or a graduate school in the biomedical sciences are scientists," he said. "I think science and religion address very different types of questions, and they shouldn't overlap."
Dr. Dini, who said he had no intention of changing his policy, declined to address the question of his own faith. But university officials and several students who support him say he is a religious man.
"He's a devout Catholic," said Greg Rogers, 36, a pre-med student from Lubbock. "He's mentioned it in discussion groups."
Mr. Rogers, who returned to college for a second degree and who said his beliefs aligned with Dr. Dini's, added: "I believe in God and evolution. I believe that evolution was the tool that brought us about. To deny the theory of evolution is, to me, like denying the law of gravity. In science, a theory is about as close to a fact as you can get."
Another student, Brent Lawlis, 21, from Midland, Tex., said he hoped to become an orthopedic surgeon and had had no trouble obtaining a letter of recommendation from Dr. Dini. "I'm a Christian, but there's too much biological evidence to throw out evolution," he said.
But other students waiting to enter classes Friday morning said they felt that Dr. Dini had stepped over the line. "Just because someone believes in creationism doesn't mean he shouldn't give them a recommendation," said Lindsay Otoski, 20, a sophomore from Albuquerque who is studying nursing. "It's not fair."
On Jan. 21, Jeremiah Glassman, chief of the Department of Justice's civil rights division, told the university's general counsel, Dale Pat Campbell, that his office was looking into the complaint, and asked for copies of the university's policies on letters of recommendation.
David R. Smith, the Texas Tech chancellor, said on Friday afternoon that the university, a state institution with almost 30,000 students and an operating budget of $845 million, had no such policy and preferred to leave such matters to professors.
In a letter released by his office, Dr. Smith noted that there were 38 other faculty members who could have issued Mr. Spradling a letter of recommendation, had he taken their classes. "I suspect there are a number of them who can and do provide letters of recommendation to students regardless of their ability to articulate a scientific answer to the origin of the human species," Dr. Smith wrote.
Members of the Liberty Legal Institute, who specialize in litigating what they call religious freedom cases, said their complaint was a matter of principle.
"There's no problem with Dr. Dini saying you have to understand evolution and you have to be able to describe it in detail," said Kelly Shackelford, the group's chief counsel, "but you can't tell students that they have to hold the same personal belief that you do."
Mr. Shackelford said that he would await the outcome of the Justice Department investigation but that the next step would probably be to file a suit against the university.