The Catholic Church is famously conservative, but San Francisco’s archdiocese is carving out new ground on the right even for that religion as it tries to require its teachers to reject homosexual relations and other “gravely evil” behavior in their lives.

Only a handful of U.S. dioceses have added such forceful language to their teacher conduct codes in recent years requiring conformity to church doctrine in their public and private lives, experts say. Oakland, Santa Rosa and Cleveland were foremost among them — but none has pressed the point home as adamantly as San Francisco Archbishop Salvatore Cordileone. And Oakland and Santa Rosa have backed down from their pushes.

“I don’t know of anybody else doing this in the way San Francisco is,” said Lisa Fullam, associate professor of moral theology at the Jesuit School of Theology of Santa Clara University. “That having been said, it’s not that the archbishop isn’t accurately representing Catholic teaching. It’s just how he is choosing to do it that is a bit different.”

How this came about in San Francisco, the left coast bastion of all things liberal, shouldn’t come as a surprise to anyone with inside knowledge of the church, said the Rev. James Bretzke, a Boston College professor of moral theology.

The 195 archdioceses and dioceses in the United States have long been run as quasi-independent fiefdoms by their bishops, a few of whom stand out as plowing to the right. Prominent among them are those trained at the ancient Pontifical Gregorian University in Rome as canon lawyers — including Cordileone, his friend Bishop Robert Vasa of Santa Rosa and Bishop Thomas Olmsted of Phoenix.

Going against the wind

Their legal training, Bretzke said, means they are more prone to adhere strictly to church law — which has always held that homosexual relations, contraception, abortion and same-sex marriage are sins. And all three men have made waves with prominently conservative stances, even as Pope Francis admonishes against focusing on divisive issues such as same-sex marriage and birth control.

“I believe these men are acting out of sincere conviction, because clearly the ecclesial winds have shifted,” said Bretzke, who taught at the University of San Francisco and in Berkeley before going to Boston. “This is not the way to put winds in your career sails anymore. Whatever you want to say about them, you cannot say they are political opportunists.”

Cordileone told his almost 500 school employees this month to “affirm and believe” morality clauses in an updated handbook that brands as “gravely evil” sex outside of marriage, homosexual relations, abortion, masturbation and the viewing of pornography. Teachers have spoken out against the dictate, more than 6,000 people around the nation have signed an online petition opposing it, and the union representing archdiocese teachers is negotiating over the language.

Vasa proposed similarly strict moral guidelines for teachers two years ago that collapsed under pressure. Olmsted angered liberals in 2010 by declaring a nun excommunicated because she approved an abortion for a woman pregnant with an 11-week fetus whose birth would have killed her.

Eight California legislators including Sen. Mark Leno and Assemblymen David Chiu and Phil Ting, all San Francisco Democrats, sent Cordileone a letter last week asking him to excise the new teacher handbook language, calling it “an alarming message of intolerance.” The bishop responded with a letter contending that “a lot of misinformation” was being circulated about his proposal.

“My point is: I respect your right to employ or not employ whomever you wish to advance your mission,” the archbishop wrote. “I simply ask the same respect from you.”

Representatives of most other dioceses in Northern California either did not return calls for comment about the situation in San Francisco, or sent brief responses such as the one from Liz Sullivan, spokeswoman for the Diocese of San Jose. She wrote in an e-mail that her organization — noted for welcoming lesbian, gay, bisexual and transgender worshipers at its services — “does not comment on what is happening in other dioceses.”

“The policies of the Diocese of San Jose remain unchanged,” she wrote.

Support from Santa Rosa

In Santa Rosa, however, Bishop Vasa wholeheartedly endorsed Cordileone’s latest move — unsurprising, considering his failed 2013 proposal bore the same tones. Oakland Bishop Michael Barber’s similar attempt at teacher guidelines last year was also diluted under pressure.

“The shock and surprise that the church has standards and that it will actually enforce them should not be happening,” Vasa said. “Of course you need a code of ethics. Look at UPS. They have strict dress codes, hair codes, business conduct codes. Why should the church be different?

“People have got to know that the church has moral standards,” Vasa said. “Whether they are adhered to strictly or not, we still have standards. And we as bishops have to represent the clear and moral teachings of the church. These are not new teachings.”

The local conservative stance finds more resonance in Cleveland than most other places. There, Bishop Richard Lennon expanded the morality clause last year for his diocese’s teachers that banned activities including same-sex relations, pornography viewing and cohabitation outside marriage on pain of being fired.

Diocese spokesman Robert Tayek said the move was made to “be more specific” at a time of growing moral need.

“Like the Archdiocese of San Francisco, we here in the Cleveland Diocese recognize that now, more than ever, the secular culture is offering a view of life and humanity that is often at odds with Christ’s truth as presented through the Catholic Church,” read a diocese statement forwarded by Tayek. “In response to that reality, we have added language to our teacher contracts.”

In Santa Rosa, Vasa released a revised code of conduct this month for school employees that requires them to conform to church teachings — but leaves out mention of abortion, same-sex marriage and other controversial subjects that derailed his 2013 plan. “It’s a policy in process of reviewing,” he said.

'Complex’ policies

Although the wording in San Francisco is different from his own, Vasa said, he regards his friend Cordileone as reaching for similar clarity on moral dictates. He adding that such policies are “complex” and that “Chronicle sound bites are not useful.”

“The San Francisco archbishop is not a mean-spirited person,” Vasa said. “But he is a person who knows the teachings of the church and knows they are not bad for us.

“We have a phrase: 'Good morals make good medicine,’” he said. “I’d say good morals make good leadership, good leaders, good teachers — all across the board.”

Kevin Fagan is a San Francisco Chronicle staff writer. E-mail: kfagan@sfchronicle.com

Twitter: @KevinChron