*Last Updated Nov. 4, 2015 to reflect Tuesday's election results
Four years ago, Massachusetts passed an anti-discrimation law offering protection to transgender people in areas such as employment, housing, lending and education. Legislators specifically avoided including public accommodations in the law, but the idea that transgender people would use bathrooms and locker rooms that didn't conform with the sex they were assigned at birth caused concern for some.
That issue is still controversial. The legislature is now considering a public accommodations bill that once again has triggered heated opposition.
"We think it's important for all Massachusetts citizens to have their privacy and security protected in intimate spaces," said Andrew Beckwith, president of the Massachusetts Family Institute. "If this were passed, women would be forced to change next to anatomical, biological males."
The same argument is taking place all over the country. Legislators in states including Florida, Minnesota, Nevada and Wisconsin have introduced bills that would limit students or adults to using bathrooms appropriate to the gender listed on their birth certificates, as opposed to their current gender identity.
This spring, an anti-discrimination ordinance in Charlotte, N.C., was defeated due to objections about bathroom privacy. In Houston, voters rejected an anti-discrimination measure on Tuesday for the same reason.
Houston Astros star Lance Berkman aided the opposition.
"My wife and I have four daughters and Proposition 1 will allow troubled men who claim to be women to enter women's bathrooms, showers and locker rooms," he said in ad against the anti-discrimination measure.
Transgender advocates say this is all just fear-mongering.
"There's this fear that this person who is different is different in a way that's predatory," said Robin McHaelen, executive director of True Colors, a social service nonprofit that works with LGBT youth in Connecticut. "As far as I know, there's never been an incident with a transgender person assaulting someone in a bathroom. People just want to pee in peace."
That same assertion has been made by groups such as the Human Rights Campaign and the American Civil Liberties Union. Officials in states with public accommodation provisions, such as Connecticut, Hawaii, Iowa and Oregon, have stated they have seen no evidence of sexual assault or other such problems as a result.
By contrast, there have been documented examples of transgender people being harassed or assaulted for going in the "wrong" bathroom, including a videotaped attack in 2012 in Maryland that went viral on social media.
"You just want to use the bathroom and get back to what you're doing," said Mara Keisling, executive director of the National Center for Transgender Equality. "The safest way, the most appropriate way, the way to bother the people least is for people to use the restroom that's appropriate for their gender identity."
If people misbehave in a public restroom, they should be prosecuted, Keisling said -- but that's true whether the person is transgender or not.
But according to Brad Dacus, president of the Pacific Justice Institute, which is now collecting signatures for a ballot measure to repeal a California law that allows transgender people to use facilities of their choice, the simple presence of a transgender woman in a women's bathroom or locker room can make young girls feel "visually violated."
"The issue is not that transgenders are somehow prone to attacking other users of a bathroom or a locker room," he said. "The focus is on the right of a young girl to not feel herself as having her privacy violated in the most intrusive way."
The proposed California initiative would impose fines of at least $4,000 when transgender people use facilities according to the gender they weren't assigned at birth. It would make exceptions, however, for individuals whose gender status has been confirmed by medical examination or the courts.
Last month, a federal court ruled against a transgender boy who sought to use the boy's room at a Virginia high school. The judge ruled he would have to use a single-stall bathroom instead. The Obama administration weighed in on the case, with justice and education department lawyers writing a brief arguing that "prohibiting a transgender male student from using boys' restrooms, when other non-transgender male students face no such restriction, deprives him not only of equal educational opportunity but also of equal status, respect and dignity."
Signs on the lawn of people protesting an anti-discrimination ordinance in San Antonio, Texas. (David Kidd)
The number of people, and public bathrooms, this is likely to impact is rather low. The most widely-cited recent estimate, from the Williams Institute at UCLA's law school, suggests that there are less than 700,000 transgender adults in the United States.
But transgender equality has emerged as a civil rights battle, raising issues that are familiar from earlier movements. Worries about mandated unisex bathrooms fueled some of the opposition to a federal Equal Rights Amendment to protect women in the 1970s. Black people in the 1950s and 1960s were seeking not just voting and employment rights but the chance to use the same pools, drinking fountains, lunch counters -- and bathrooms -- as white people.
In a recent opinion piece on Huffington Post, Massachusetts state Rep. Paul Heroux made this comparison explicit.
"The argument that a non-transgender person feels uncomfortable with a transgender person using the same bathroom ... is the same argument that was once made of people of color using public bathrooms, seating on public transportation, public drinking fountains and more," Heroux wrote. "It is a lack of understanding at best, and hateful at worst."