SALT LAKE CITY - Matthew Petersen and 55 other medical students at the University of Utah have sent a letter to one of their professors, demanding he explain his views on same-sex marriage.

"We saw his signature on the amicus brief that said that legalizing same-sex marriage would cause 900,000 abortions," he said. "[That] didn't make sense to us."

Dr. Richard Farnsworth was among 100 medical professionals who signed an amicus brief to the Supreme Court, arguing that same-sex marriage is bad for families.

They claim legal gay marriage will lead to an additional 900,000 abortions and 600,000 more children being born to unmarried women.

"Basically, because we are students here and he is an adjunct faculty here, we had some questions that were regarding what he put his name to, the research he backed by signing," Petersen said.

Farnsworth isn't the only educator coming under fire for signing the brief.

UVU President Matthew Holland also signed it, and is facing criticism from within the faculty and student body. Farnsworth would not return calls on Tuesday.

The university issued a statement saying it stands behind his right to express his personal views.

"The University recognizes the right of its faculty to express their individual opinions, and in signing the brief, Dr. Farnsworth was expressing his personal views and not those of the University of Utah," the statement read.

Critics are hoping Farnsworth will show scientific research to back up his claims.

"Really, our intentions are to promote good science and to promote good medicine and good healthcare for everyone in Utah, regardless of age, sex, race religion, gender identity or sexual orientation," Petersen said.