Summing up, Silver Fern Farms' lawyer Mr Cleary said Mr Kupa would wear the hat if the air-conditioning was fixed, providing cooler temperatures, but it had not been fixed so Mr Kupa would continue to not wear his hat if he got his job back.
He said the hat was part of personal protective equipment employees had to wear for health and safety.
If an employee failed to wear it they could be warned, but choosing deliberately not to wear it was dismissable.
He said Mr Kupa was "making up his own safety rules".
Mr Kupa's lawyer Simon Mitchell said the case's starting point was the hat - there was no evidence they were protective and they were not always mandatory, with managers allowing workers to take them off at different times, which showed their inadequacy.
Mr Mitchell said his client could not find another job because he had worked in the industry for a long time and the skills were not easily transferable.
Judge Bruce Corkhill said at the end of the two-and-a-half day hearing yesterday he would reserve his decision.
