An Idaho state law banning transgender women from competing in women's sports has some notable athletic figures calling for the NCAA to move 2021 men's basketball tournament games from the state capital of Boise.

Tennis icon Billie Jean King, soccer star Megan Rapinoe, women's basketball standout Sue Bird and former NBA player Jason Collins were among the 400 athletes to sign a letter sent Wednesday that criticizes the state's Fairness in Women's Sports Act, also known as HB 500.

HB 500 was signed into law by Idaho Gov. Brad Little on March 30. It goes into effect July 1 and states in part, "athletic teams or sports designated for females, women, or girls shall not be open to students of the male sex." The law allows for girls and women to have their genitals checked if their biological sex is challenged.

Advocacy groups have sharply criticized the law, and now the NCAA games scheduled to be played March 18-20, 2021 at ExtraMile Arena on the Boise State campus could be in danger.

Sports Illustrated obtained the letter to the NCAA and noted that it states, "Given Idaho's adoption of a discriminatory law that directly impacts college athletics, violates NCAA values, and undermines the dignity and well-being of NCAA athletes, Idaho schools no longer qualify to host NCAA events."

More than 60 organizations signed the letter, according to SI. Advocacy groups indicated that the NCAA is unhappy with the Idaho law.

"Transgender athletes deserve the same dignity and respect entitled to all NCAA athletes," Rodrigo Heng-Lehtinen, deputy executive director for Policy and Action with the National Center for Transgender Equality, said in the letter. "Because of HB 500, that simply isn't possible in Idaho. We applaud the NCAA for speaking out against HB 500 and now encourage them to back up their words with action."

The NCAA moved events out of North Carolina during the 2016-17 season after that state passed controversial HB2 -- often referred to as the "Bathroom Bill." That legislation required transgender people to only use bathrooms and changing rooms that corresponded to the gender listed on their birth certificates.

The NBA pulled its 2017 All-Star Game out of Charlotte before returning to play it in the city in 2019 after some modifications.

In Idaho, the American Civil Liberties Union and Legal Voice have filed a lawsuit claiming HB 500 violates the U.S. Constitution because it is discriminatory and rates as an invasion of privacy.

Two plaintiffs are part of the suit. One is an unidentified high school student in Boise and the other is Boise State sophomore Lindsay Hecox, who hopes to compete on the Boise State women's cross country team. Hecox, 19, competed on a boys' team in Moorpark, Calif., while in high school before transitioning.

"Transgender people belong everywhere -- and that includes in sports and in Idaho," said Arli Christian, campaign strategist for the ACLU. "While the lawsuit against the state of Idaho moves through the courts, it is important for everyone to speak out so that Idaho -- and the rest of the country -- sees how misguided and dangerous this law is."

--Field Level Media

Comment about idaho transgender law could lead to removal of ncaa tourney games