In Arizona, the owner of a small bakery refused to serve a gay couple who had ordered a wedding cake, citing religious principle.

In New Mexico, a photographer declined to work a gay couple’s wedding, also citing religious beliefs that homosexuality is a sin.

These scenarios raise big questions about discrimination: Does a business have the right to refuse service to anyone it chooses, based on the owner’s religious convictions? Do civil-rights protections extend to people based on their sexual orientation?

The issue comes to a head this week in Arizona, where Gov. Jan Brewer must sign or veto a state law protecting businesses that refuse service to customers for religious reasons.

The bill, which cleared the Arizona Legislature last week, states, “A person whose religious exercise is burdened ... may assert that violation as a claim or a defense in a judicial proceeding.” It updates existing Arizona law on the “exercise of religion” and protects businesses, corporations and people from lawsuits if they deny services based on a “sincere” religious belief.

Opponents call the bill state-sanctioned discrimination. They envision gay couples being thrown out of restaurants or being denied medical treatment. There’s an implied danger, they note, that a business might try to discriminate against other people claiming religious beliefs. They’re pressuring Brewer to veto it.

Supporters say the bill is about protecting religious freedom, not about allowing discrimination. They cite the case of that New Mexico photographer, who was sued for refusing to take wedding pictures of a gay couple.

Brewer has five days to sign or veto the bill once it gets to her desk. She hasn’t said what she will do. She has said she supports a business’s freedom of choice but remains unsure whether that has to be put into state law.

Several prominent members of Brewer’s Republican Party are urging a veto, which would seem the prudent choice. The courts should be trusted to sort out this debate.

There’s only one hitch to the veto route: Remember that New Mexico photographer who was sued? The case went all the way to the New Mexico Supreme Court, which ruled that businesses have no right to refuse service to anyone based on religious conviction. The ruling has no direct bearing on Arizona law, but it’s easy to see the same scenario playing out there if Brewer vetoes this bill.

The bill’s one major shortcoming: its opens a potential Pandora’s box — allowing a little discrimination, however justified, might lead to more.

Even so, Arizona would be better off if the governor signs this measure. It would be better to face the inevitable court challenge of the new law than to repeat what already has been decided next door in New Mexico.