A teacher who is aggrieved by a decision of a board of trustees on the nonrenewal of the teacher's term contract may appeal to the commissioner for a review of the decision of the board of trustees in accordance with the provisions of Subchapter G. The commissioner may not substitute the commissioner's judgment for that of the board of trustees unless the board's decision was arbitrary, capricious, unlawful, or not supported by substantial evidence.
Tex. Educ. Code § 21.209