This story has been updated throughout.

AUSTIN — An effort by three University of Texas at Austin professors to block the implementation of the state's divisive campus carry law has failed, after a federal judge on Monday denied their request for a preliminary injunction.

U.S. District Judge Lee Yeakel, ruling just two days before classes begin at UT, rejected the key arguments made so far against the firearms measure. Among those were the notions that allowing guns in classrooms violates free speech and equal protection rights.

Though the lawsuit to overturn the law remains alive, the judge said the professors had "failed to establish a substantial likelihood of ultimate success on the merits of their asserted claims."

"It appears to the court that neither the Texas Legislature nor the Board of Regents has overstepped its legitimate power to determine where a licensed individual may carry a concealed handgun in an academic setting," he wrote in an 11-page opinion.

Renea Hicks, an attorney for the professors, said the group was "obviously disappointed." He said his team would "begin to pull together the evidence and facts for the trial and hope things go smoothly on campus in the meantime."

"Sometimes public policy is so terrible and so extreme that it takes the courts ... by surprise, and a little while to catch up," he said.

UT president Gregory Fenves said in a written statement that the university would continue to work with faculty members concerned about the law. He added that he's committed to upholding the school's "core values" of academic freedom and free speech.

Attorney General Ken Paxton, a Republican, said that he was "pleased, but not surprised" by the decision.

"There is simply no legal justification to deny licensed, law-abiding citizens on campus the same measure of personal protection they are entitled to elsewhere in Texas," he said in a written statement.

The law, which went into effect this month, allows the licensed carrying of concealed handguns in most public university buildings.

Unlike private universities, state schools cannot completely opt out of campus carry. But the law allows public school officials to establish some "gun-free" zones, as long as they are "reasonable" and don't have the effect of generally prohibiting guns on campus.

Even with those guidelines, the idea of guns in classrooms has been a point of contention.

Though UT tested the limits of the legislation — allowing faculty, for instance, to ban guns in their offices — the school joined every other public college or university in Texas in allowing carry in class. To do otherwise, officials said, would violate the law.

That decision came even though UT officials expressed their unease with the idea.

"Every member of the working group — including those who are gun owners and license holders — thinks it would be best if guns were not allowed in classrooms," the school's campus carry working group wrote in its final report.

Attorneys for the professors — Jennifer Lynn Glass, Mia Carter and Lisa Moore — nonetheless went to court press their case that guns would chill free speech.

"They know that they will begin to curtail discussions," Hicks said at a hearing this month in Austin. Allowing guns in classrooms, he said, "does invariably, inevitably ... narrow the scope of the academic discussion."

But Anne Marie Mackin, an assistant attorney general representing UT, said the idea that the law would impinge academic expression was in "rooted in assumptions and prejudices." And Yeakel concurred, saying the professors sought too broad of a definition of academic freedom.

"Their First Amendment claim is and must be bottomed on their right to speak and teach freely," the judge wrote. "Neither the campus carry law nor the campus carry policy forbids them from doing so."

Yeakel also rejected the professors' argument that the law is unconstitutionally vague, saying that UT's policy is relatively clear. And though he wrote at length about the equal protection claim, the judge also said that argument wasn't likely to succeed.