NASHVILLE (AP) - Tennessee's largest teachers' union is suing Gov. Bill Haslam and his education commissioner.

The Republican governor and Commissioner Kevin Huffman are included in the latest Tennessee Education Association lawsuit, which also includes the Knox County Board of Education as a defendant.

It's the second lawsuit this month the agency has filed against the Knox County board. Both claim the student test scores used to assess two teachers' performances were flawed and cost them bonuses.

TEA President Gera Summerford says the governor and commissioner were included in the lawsuit because "this really is a state issue."

The organization has long argued that the Tennessee Value-Added Assessment System shouldn't be relied upon because it's a statistical estimate.

The group has proposed legislation to prohibit TVAAS scores from being tied to teacher licensing.