The recent flurry of state bills giving religious exemptions from certain laws -- including the Arizona law that Gov. Jan Brewer (R) just vetoed -- raises a question: How many states already provide heightened protection for the exercise of religion?

The answer? Thirty-one, 18 of which passed state laws based on the 1993 federal Religious Freedom Restoration Act. The protections in an additional 13 states came through court rulings. Here's a map of which states have added protections and which do not:

"These state RFRAs were enacted in response to Supreme Court decisions that had nothing to do with gay rights or same-sex marriage," explained University of Virginia law professor Douglas Laycock in an e-mail. "And the state court decisions interpreting their state constitutions arose in all sorts of contexts, mostly far removed from  gay rights or same-sex marriage. There were cases about Amish buggies, hunting moose for native Alaskan funeral rituals, an attempt to take a church  building by eminent domain, landmark laws that prohibited churches from modifying their buildings – all sorts of diverse conflicts between religious practice and pervasive regulation."

A new political fight has emerged in part because some of these more recent proposals are shifting the definition of when citizens can opt out on religious grounds. The federal law says that the government may not pass a law that “substantially burdens a person’s exercise of religion.” But now some businesses -- including the ones who are challenging the Affordable Care Act's contraception coverage mandate in the Supreme Court -- are arguing that they don't have to meet this substantial-burden test.

Kansas, for example, already has the Kansas Preservation of Religious Freedom Act. But its state House passed a bill that would have allowed any individual to refuse to recognize same-sex couples or provide them with services on religious grounds, without having to show that such compliance would substantially burden their ability to exercise their faith.

This week the Kansas state Senate declined to take up the House bill. Laycock, who described that proposal as extreme, wrote that both advocates and opponents of these laws are poisoning Americans' views of what religious freedom means.

"The conflicts over gay rights and contraception are polarizing the country and endangering religious liberty more generally," he wrote. "Neither side in these fights seems to have any respect for the liberty of the other."