A Utah State University professor is defending signing an amicus brief urging the Supreme Court to uphold state gay marriage bans.

Richard Sherlock, a professor of philosophy at Utah State University (USU), was among the “100 scholars of marriage” who signed an amicus brief in support of state bans on gay marriage in a case argued before the Supreme Court last month.

In the brief, attorney Gene Schaerr argues, among other things, that allowing gay couples to marry would lead to 900,000 additional abortions over the next 30 years.

Sherlock told the Herald Journal in Logan that allowing gay couples to marry nationwide would lead to plural marriages.

“You've got thousands of laws in states a well as the federal law,” he said. “Everything would have to change, and what would have to happen logically is all the other things (including polygamy and polyandry) would have to be acceptable,” he said.

Utah Valley University (UVU) President Matthew Holland also joined the brief, the only university president to do so, triggering a protest by scores of UVU professors and staff.

(Related: University president's opposition to marriage equality draws protest.)