In the face of a lawsuit, a Missouri state senator defended on Saturday a new state law that will prohibit teachers from communicating privately with students over the Internet.

A teachers group filed a lawsuit Friday afternoon contending the new lawsuit violates free speech and other rights, but the senator who sponsored it says it does nothing of the kind.

It doesn't stop any avenue of communication whatsoever, it only prohibits hidden communication between educators and minors who have not graduated, said state Senator Jane Cunningham, a St. Louis Republican and key sponsor of the law.

School districts statewide are being required to adopt new policies to comply with the law beginning January 1, but the Missouri State Teachers Association said in its lawsuit that banning social media contact is unconstitutional.

The act is so vague and over-broad that (teachers) cannot know with confidence what conduct is permitted and what is prohibited and thereby 'chills' the exercise of first amendment rights of speech, association, religion, collective bargaining and other constitutional rights, says the lawsuit, filed in Cole County Circuit Court in the state capital of Jefferson City.

The lawsuit names the state, the governor and attorney general as defendant and seeks a court injunction and hearing.

Representatives of the teachers' association and other groups said they are unaware of any state with a law as restrictive as the one in Missouri.

The law permits teacher-student contact if the Internet site can be viewed by parents, administrators or the public. Teachers and students can still e-mail and text each other as long as someone is copied, Cunningham said.

Cunningham said the teachers' association supported the law and helped draft some of the language last spring.

It seems like they are suing their own work, she said.

But Todd Fuller, spokesman for the teachers' association, said Saturday the group did not review the final language on social media usage. That language on social media contact is just one part of a larger bill intended to discourage private relationships between teachers and students that have sometimes led to sexual abuse.

Teachers have said the vast majority of their private contacts with students over the Internet are education-related and can be helpful, especially for shy students. The lawsuit made a similar point.

Plaintiffs have used and are using non-work-related social networking sites as an important avenue for contact with students, both during emergencies and for everyday educational issues, such as when a student has difficulty with a classroom assignment or identifying bullying, the lawsuit states.

(Writing and reporting by Kevin Murphy; Editing by Mary Wisniewski and Jerry Norton)