Major companies including Nike and Altria and 22 Democratic attorneys general are asking a federal appeals court to block an Idaho law barring transgender girls and women from female high school and college sports teams.

The Trevor Project, a nonprofit that focuses on suicide prevention among gay and transgender youth, and the groups GLBTQ Legal Advocates and Defenders and the National Center for Lesbian Rights, also filed briefs opposing the law late Tuesday. In this they joined numerous other individuals and groups who filed amicus curiae briefs earlier Tuesday opposing the law, including both transgender and cisgender female athletes, numerous medical groups and three former Idaho attorneys general.

“When transgender youth are permitted to freely express their gender identities, they experience similar mental health outcomes to their cisgender peers, but when their identities are disaffirmed or invalidated they are placed at increased risk of depression and self-harm,” the Trevor Project wrote in its brief. “In the realm of sports, as in other aspects of their lives, transgender youth thrive when their identities are recognized and supported, but suffer significantly when they are excluded or unfairly singled out.”

State lawmakers passed House Bill 500, also called the Fairness in Women’s Sports Act, this year, but a couple of student athletes, backed by the American Civil Liberties Union of Idaho and the progressive feminist group Legal Voice, are suing to have it declared unconstitutional, and a federal judge has put its enforcement on hold as the case winds through the courts. The Alliance Defending Freedom, a socially conservative Arizona-based group that helped to craft the bill, is asking the U.S. Ninth Circuit Court of Appeals to overturn the stay and let Idaho enforce the law. Although similar laws have been proposed in other states, Idaho is the only one with such a law on the books now. The bill’s supporter say it is meant to protect female athletes from unfair competition with people who were born male.

Wednesday’s brief from the Democratic attorneys general of 21 states and the District of Columbia means that the attorneys general of 36 states not including Idaho have weighed in on the law — a group of 14 Republican attorneys general filed a brief supporting the law a month ago. The Democrats in their brief say many of their states have policies against discriminating against transgender people, which they say “has no legitimate basis and serves only to injure a group that is perceived as different.”

“The amici states’ shared experience in administering their anti-discrimination policies demonstrates that permitting transgender students to participate in athletic programs consistent with their gender identity benefits all students and does not compromise opportunities for cisgender students,” the Democrats wrote. “Because the sole function of the Act is to exclude and stigmatize transgender students like (Lindsay Hecox, one of the plaintiffs), the Act violates equal protection under any level of scrutiny.”

The companies that joined a brief opposing the law are Amalgamated Bank; the tobacco company Altria; the software company Asana; ice cream maker Ben and Jerry’s; Lush Cosmetics; the Vermont-based snowboard company The Burton Corporation; and the globally known sports clothing, sneaker and equipment company Nike. Ben and Jerry’s and Nike have been vocally supportive of gay rights for years; Chris Mosier, a transgender athlete who is sponsored by Nike, has been one of the prominent voices pushing against Idaho’s law and came to the state during the legislative session to speak out against the bill.

The companies in their brief say they are committed to fostering inclusive workplaces and that their transgender employees and transgender children of employees could be harmed by the law.

“LGBTQ employees, students, and athletes — indeed all of society — only can excel when workplaces and all aspects of American life are free from discrimination,” they wrote.

Reporter Nathan Brown can be reached at 208-542-6757. Follow him on Twitter: @NateBrownNews.