The school administrator was previously fined two day's pay for the incident.
Waroona District High School Deputy Principal David Mattin has had two finding of misconduct against him quashed after it was found he acted reasonably when pushing students.
The Education Department failed to prove his actions were unreasonable in a decision released by the WA Industrial Relations Commission this week.
In March 2017 Mr Mattin is said to have blocked the doorway of a student he was supervising in the "reflection room" before pushing the student in the chest.
The West reports the department found the degree of physical force used was “not reasonable or necessary” to manage the student.
“It is not clear how the use of force was unreasonable,” Commissioner Damian Matthews said in his ruling.
In a separate incident on the same day Mr Mattin grabbed the arm of another student who was attempting to leave the reflection room while under his supervision.
A report from the department found the student, who was sent to Mr Mattin for bad behaviour, was not being aggressive and the teacher's actions were not an appropriate response.
The department was criticised by Commissioner Matthews. He said a report lodged by the department failed to explain alternative actions the teacher should have taken.
“In my view the investigation report contains what I might colloquially refer to as ‘conversation starters’ rather than an analysis of reasonableness,” the ruling said.
State School Teachers Union president Pat Byrne told The West the ruling helped provide more clarity on the meaning of “reasonable force”.
“The Act clearly allows for reasonable force to be used,” she said in an interview with The West.
“So on that basis it’s not good enough for the employer to simply say all contact is unreasonable.”
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