Gov. Charlie Baker on Tuesday signed the CROWN Act, a bill that bans bias based on hairstyle in the state of Massachusetts.

The legislation specifically prohibits discrimination based on "natural and protective hairstyles such as braids, locks, twists, Bantu knots and other formations."

The name of the CROWN Act stands for "Create a Respectful and Open World for Natural Hair," and it's rooted in the case of a Massachusetts charter school that was under scrutiny in 2017 for a policy that banned hair braid extensions. The American Civil Liberties Union of Massachusetts filed a complaint against the Mystic Valley Regional Charter School for disciplining and suspending Black and biracial students based on this policy.

The parents of two 15-year-old students, Deanna and Mya Cook, helped bring the issue to light, and the sisters were at the State House Tuesday for the signing ceremony.

"Many across Massachusetts, particularly Black women, find themselves in positions similar to Mya and Deanna," Rep. Steven Ultrino, a Democrat representing Malden and a sponsor of the bill, said at the time. "These practices that led to discrimination claim to support professionalism, but that begs the question: what does wearing your hair in braids have to do with being professional?"

After Massachusetts Attorney General Maura Healey — now running for governor —stepped in, the school removed the rule.

The bill passed the House and Senate unanimously.

California became the first state to ban workplace and school discrimination against Black people for wearing hairstyles like braids, twists and locks. Since then, over a dozen states have followed, advocating for their own versions of the CROWN Act.