In a pivotal judgment for transgender rights, the Supreme Judicial Court of Maine ruled Thursday that transgender students should be allowed to use the bathroom of their choice. Nicole Maines, the plaintiff in the suit, was denied permission to use her school’s girls’ bathroom because she is transgender. The Maines family sued the school district for violating their Maines’ rights in 2009, according to The Associated Press.

"As parents all we've ever wanted is for Nicole and her brother, Jonas, to get a good education and to be treated just like their classmates, and that didn't happen for Nicole," Wayne Maines said in a statement, AP reported. "What happened to my daughter was extremely painful for her and our whole family, but we can now close this very difficult chapter in our lives."

Transgender is a term assigned to people who identify with or express a gender identity that is different from their biological sex at birth. Experts believe that any number of factors can contribute to why people are transgender. Biological theories say that genetic influences and prenatal hormone levels could contribute to transgender identification. Early-life experiences as well as events later in adulthood are also believed to contribute to the development of transgender identities.

Gender identity refers to an individual’s “internal sense of being either a male or female or, perhaps, neither.” We’re assigned a biological sex at birth. But, the thinking goes, our gender identity is formed more in the social context. Things like behavior, clothing, and voice are all forms of gender expression.

According to AP, Maines was born a boy, but has identified as female since age 2. In elementary school, Maines wanted to use the girls’ bathroom, but her school denied that request, allowing her to use the staff bathroom instead. Thursday’s ruling took into account how difficult it can be for schools to decide what’s best when the students are so young, but erred on the side of caution. “Particularly where young children are involved, it can be challenging for a school to strike the appropriate balance between maintaining order and ensuring that a transgender student’s individual rights are respected and protected," the ruling said, according to WMTW.

Melissa Hewey, the attorney for the school district, said that the defendants appreciated that the ruling provided clarity to an otherwise challenging situation. The district understand the court’s decision and will take the necessary steps to comply with the law.

"This is a momentous decision that marks a huge breakthrough for transgender young people," said Jennifer Levi, the Maines family attorney.