A federal appeals court says a former suburban Philadelphia teacher fired for writing derisively about students on her blog can't invoke free speech in suing to get her job back.

The 3rd U.S. Circuit Court of Appeals on Friday affirmed a judge's decision to throw out Natalie Munroe's lawsuit against the Central Bucks School District because her posts did not rise to the level of constitutionally protected expression.

The majority in the 2-1 decision says the interests of the district, a public employer, to maintain the trust of its students and parents outweighed Munroe's right to free speech.

The district fired Munroe in 2012 after a student discovered the blog and posted it on Facebook.

Lawyers for Munroe and the school district did not immediately return telephone messages.