David Parker was arrested last year when, after his son was given a book about gay families by a teacher, he refused to leave Joseph Estabrook Elementary School unless school officials agreed to notify him before any discussion including homosexuality took place in front of his son. Months later the charges were dropped.

Parker and his wife, along with another set of parents, are now filing a civil-rights lawsuit against the principal of Joseph Estabrook Elementary School, the superintendent and other school officials, reports Yahoo News:

The suit, according to the parents’ attorney, will contend that the school system violated the parents’ civil rights because they weren’t notified about the books or discussions in class, reported the Boston Globe.

The principal and other school system officials have maintained that the material was about families, not sexuality, according to the Globe. Parker claims the town violated his religious freedom by including homosexuality in the curriculum without notifying him.