A student in Massachusetts is suing his middle school for the right to wear t-shirts featuring anti-transgender messages.

Lawyers for Liam Morrison are asking a court to issue a preliminary injunction to prevent Nichols Middle School in Middleborough, Massachusetts from enforcing a ban on t-shirts that are “likely to be considered discriminatory, harassing and/or bullying to others,” Boston.com reports. The lawyers contend that the school’s policy, as applied to Morrison earlier this year, constitutes “viewpoint discrimination” and infringes on his First Amendment right to free speech.

According to the complaint filed last month by the Alliance Defending Freedom (ADF) and the Massachusetts Family Institute on behalf of Morrison, the 12-year-old believes “that there are only two sexes, male and female, and that a person’s gender (their status as a boy or girl, man or woman) is inextricably tied to sex.”

...The student’s father later wrote an email to Middleborough Superintendent Carolyn Lyons asking why his son had been sent home for wearing the shirt. In her response, Lyons said that the message on Morrison’s t-shirt “targeted students of a protected class; namely in the area of gender identity.”