After years of student protests over discipline and dress standards, the Noble charter school network is easing its student dress code to remove restrictions on tattoos, hair styles and piercings.

Student activists and teachers had been arguing that Noble’s dress restrictions were racist, singling out styles popular in the African-American community. The new standards went into effect Tuesday, according to a letter Noble CEO Constance Jones sent to parents earlier this month.

The new dress code signals a culture shift in Chicago’s largest and highest-rated charter network that is also one of the toughest when it comes to discipline and dress code restrictions.

Noble run 18 schools in Chicago, 11 of them rated a 1-plus, the district’s highest rating. It educates  more than 12,000 students, 98 percent of whom are students of color.

“I believe this new policy on tattoos, hair styles, and piercings allows us to deepen our commitment to diversity in a way that makes our schools even more productive,” Jones wrote in the letter.

Previous dress restrictions allowed students to wear their hair “colored or highlighted only in a natural human hair color,” and insisted that any styling must not be “distracting to the academic environment [or include] unprofessional styles.” Teachers complained that forced them to manually color in students’ hair or ask them to leave the classroom. The restrictions “aim to instill habits of self-discipline and promote a strong sense of community in our schools,” the handbook says.

Students 4 Change, a group of Noble students who has long been organizing against what they consider overly restrictive measures, celebrated the news. “Although our movement was suppressed by Noble’s administration, Students 4 Change is one step closer to a system that suits the student body’s needs,” said  Diego Garcia, a junior at Mansueto High School in Brighton Park.

Starting next fall, Noble will also get rid of a strict bathroom policy particularly burdensome to female students.

In its letter the charter network said it is considering changes to other elements of the student code of conduct that have come under fire, such as a requirement to wear a black belt or a ban against chewing gum. Noble announced its head of schools will solicit feedback on the code from students, parents and staff.

The changes come following a tumultuous year marked by student and parent protest over school dress codes and discipline. On top of that, Noble founder and CEO Michael Milkie retired suddenly after revelations of a pattern of inappropriate behavior with alumni.

At the same time, teachers have continued their yearslong efforts to organize a union at all 18 Noble schools.

In November, Constance Jones stepped into the CEO role, making her the first woman, and the first African-American, to head the network. Previously, she served as president and, before that, Noble’s chief external affairs officer following stints in management at Hyatt Hotels and Johnson & Johnson.

On Wednesday, the board of Chicago Public Schools is set to renew Noble’s charter for another five years.

Noble students, meanwhile, say they still hope to see changes coming from the network, including more voice for student government.

Read the letter to parents below.