PHOENIX - A prominent Republican lawmaker in Arizona wants to link public bathroom use to birth certificates in what civil rights advocates are calling the nation's toughest anti-transgender measure.

The bill would require people to use public restrooms, dressing rooms or locker rooms associated with the sex listed on their birth certificate or face six months in jail.

The proposal had been scheduled for a vote Wednesday during a House of Representatives committee. But in an unusual scene for the usually staid halls of state government, men in dresses, women in business suits and other transgender supporters crowded into the committee room and the lobby of the House to protest the legislation.

Minutes after the meeting started, state Rep. John Kavanagh said he would delay the debate on his bill because of a paperwork error.

Arizona's measure — and the response it received on Wednesday — reflects a growing national debate over what kind of restroom can be accessed by men and women presenting as a gender other than what they were born as.

With more people identifying as transgender, state and local governments are increasingly banning gender-identity discrimination to ward off legal battles, but opponents and proponents alike complain the laws don't explicitly demand businesses provide equal access for transgender people, creating confusion over how governments, restaurants, clothing stores and other establishments must act.

One local TV station has dubbed Arizona's legislation the "Show Me Your Papers Before You Go Potty" bill, a reference to the state Legislature's sweeping 2010 immigration law.

Among those waiting to speak out against the bill on Wednesday was Phoenix resident Erica Keppler. She was born a man, but doesn't feel comfortable in men's bathrooms or locker rooms with her earrings, long hair and feminine clothing.

If the measure becomes law, Keppler said she will be forced to go to jail or expose herself as a transgender woman each time she uses a public bathroom, dressing room or locker room, which could potentially make her vulnerable to threats from men unsettled by her appearance.

"Most transgender people try to slip through public places without being noticed," Keppler said. "This will turn us into criminals."

The term transgender covers men and women whose identity does not match with their birth-assigned sex, including cross-dressers and people who don't want to alter their bodies hormonally or surgically.

Transgender people often have a hard time changing the gender on a birth certificate because many states require proof of gender treatment surgery, which is expensive and often not covered by health insurance. Other states, including Idaho and Ohio, do not allow birth certificate changes for gender, according to the American Civil Liberties Union.

Discriminating against transgender people is illegal in at least 16 states. The protections vary. Minnesota prohibits discrimination in employment, housing, education and public accommodations, while Hawaii's law only applies to housing, according to the ACLU.

More than 100 cities and counties have passed laws prohibiting gender-identity discrimination, including Phoenix, Atlanta, New Orleans and Dallas. Those laws are also not uniform. For example, Baltimore County in Maryland approved a measure in 2012 protecting transgender people from discrimination. It did not apply to "distinctly private or personal" facilities. Tennessee lawmakers tried going in the other direction with a proposal similar to Arizona's in 2012, but it failed to gain support.

Some state laws are being tested in court. In one case, a Colorado family filed a complaint with the state's civil rights office after their first-grader, who was born a boy, was prohibited from using the girl's bathroom at her elementary school.

In recent weeks, Massachusetts and California took steps to clarify their gender-identity discrimination bans and ensure equal access for transgender students at gender-segregated facilities.

In Arizona, where Republicans control state government, Kavanagh said government shouldn't allow people to use facilities based on "you are what you think you are." He said he was worried an anti-discrimination ban passed in Phoenix last month would serve as a cover for pedophiles who want to expose themselves to children of the opposite gender.

"This law simply restores the law of society: Men are men and women are women," he said. "For a handful of people to make everyone else uncomfortable just makes no sense."

Some fret anti-discriminatory laws force businesses to spend money on renovation projects in order to provide unisex facilities and avoid complaints from customers who don't want to share bathrooms and dressing rooms with transgender people. They say Arizona's proposed law would instead protect businesses from bogus complaints from people who aren't transgender.

"Someone can just say `oh, I feel like I am a woman,'" said Aaron Baer, a spokesman for the Center for Arizona Policy, a powerful conservative group. "That person can just say, `you are discriminating against me.'"

But Masen Davis, executive director for the Transgender Law Center in San Francisco, said Arizona's proposed ban would target people who look different, regardless if they are transgender or not.

"No one should have to live in a world where they have to show their papers to pee," Davis said.

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Cristina Silva can be reached at http://www.twitter.com/cristymsilva.