Six Idaho residents are suing the state in federal court, challenging a law that makes it a crime to use a public restroom that does not correspond with the sex they were assigned at birth — a law that takes effect in July and is the strictest bathroom ban in the nation.

Under the law, a person who knowingly enters a restroom, locker room or changing area that does not align with their birth sex commits a crime, punishable by up to a year in jail for a first offense and felony imprisonment of up to five years for a second offense. Idaho’s law applies to all places of public accommodation, including privately owned businesses, making it unique in the country.

“I’ve been enjoying life as a man and using the men’s restrooms hasn’t been a big deal,” said Diego Fable, one of the plaintiffs. “But this law would force me to use the women’s facilities, and doing so would only invite suspicion, questions, and raised eyebrows. I would have to face tough choices every time I leave my home: Do I know the restroom situation when I go out to eat with my friends? Do I know the restrooms available when I go to public parks to go birding? What do I do while I’m at work all day?”

Fable said the only safe option under the law would be to stay home or leave the state, leaving his community behind.

Plaintiff Peter Poe, a transgender man with a beard, said using a women’s restroom would be disruptive and could lead to harassment or assault. Amelia Milette, a transgender woman, said her job requires visiting clients’ offices that lack gender-neutral facilities; she would have to limit her food and liquid consumption to reduce the need for a restroom in public places if the law takes effect.

Republican Sen. Ben Toews, one of the bill’s sponsors, said the legislation was needed to protect women and children. He suggested that transgender people could use single-occupancy gender-neutral restrooms instead. But plaintiffs and advocates say such restrooms are scarce, and most people routinely encounter only gendered multi-occupancy facilities in public.

“This law is a dangerous and discriminatory effort to push transgender people out of public life,” said Barbara Schwabauer, senior staff attorney for the ACLU’s LGBTQ & HIV Rights Project. “If you cannot use the restroom at work, you cannot go to work. If you cannot use the restroom at school, you cannot go to school.”

The lawsuit names Idaho Attorney General Raúl Labrador as a defendant. His office said it would defend the law, which the ACLU and Lambda Legal argue violates constitutional privacy rights because it forces transgender people to disclose their transgender status, and discriminates on the basis of sex and transgender identity.

The Idaho law is the strictest bathroom ban in the nation, affecting a state that already prohibited transgender people from using bathrooms aligning with their gender in schools. At least 19 other states have adopted similar school or limited public facility bans, but only three — Florida, Kansas, and Utah — have made violations a criminal offense, and none have extended the ban to all places of public accommodation in the way Idaho’s law does. The plaintiffs argue that the law, if allowed to stand, would effectively force them to choose between criminal prosecution and public exclusion.