Updated

For Ethan St. Pierre, allowing someone who is biologically female — but self-identifies as male — to use the men's bathroom is a no-brainer.

"Look at me," said St. Pierre, who was born a woman but is now a transgender man with a beard and short hair.

"I don't want to get hurt by some woman who thinks I'm in the ladies room for the wrong reasons. I mean, clearly I don't belong there."

St. Pierre, of Haverhill, was one of hundreds of advocates at a Tuesday lobby, supporting a bill that would add "gender identity and expression" to Massachusetts's discrimination and hate crimes laws. Having this legislation would have protected St. Pierre from being fired in 2003 from his job as a security supervisor because he became a man, he said.

But opponents of the measure have deemed it "a bathroom bill," saying it would lead to a breakdown in privacy and public safety in rest rooms, locker rooms, showers and other single-sex facilities.

They contend the law would open women's bathrooms to sexual predators.

Kris Mineau, president of the Massachusetts Family Institute, said women and children in Colorado, where a similar measure has passed, have begun to fear for their safety in bathrooms.

"Are we going to have to have the bathroom police to check everybody of a different gender that goes into the women's room?" Mineau said. "We certainly are against discrimination of any members of society, but that's not the issue here."

Massachusetts is the latest state to consider banning discrimination because of transgender status. New Hampshire recently killed legislation because of the fear that transgender individuals could use any bathroom, but is reconsidering its bill Wednesday.

Thirteen other states prohibit discrimination against people who identify themselves as a different gender. Laws also exist in the District of Columbia and 93 cities and counties, according to the Transgender Law Policy Institute.

State Rep. Carl Sciortino, D-Medford, filed the Massachusetts legislation and said it is long overdue because of high discrimination rates in the transgender community and a lack of legal protection. He and other supporters said nothing in the bill diminishes laws regarding criminal conduct in bathrooms.

"This legislation guarantees equality and civil rights and in no way condones or allows or legalizes illegal behavior," he said.

St. Pierre, who is affiliated with the Massachusetts Transgender Political Coalition, agrees.

"It's never stopped perverts from going into bathroom before because it says 'female.' You don't see a guy or woman stopping at sign and saying, 'Oh, I can't go in there,"' St. Pierre said, adding there hasn't been any instance of a transgender person attacking someone in a restroom. "I don't know what the big to-do is — it's just fear-mongering."

Sciortino said the bill is in committee and public hearings are being scheduled.