He was dismissed in April under the 90-day trial clause.
He then appealed to the authority that the 90-day trial clause was not valid and that he was unjustifiably dismissed.
The construction company's managing director Tim Smith countered that the clause was valid and said the company dismissed Mr Hall as it was dissatisfied with his performance.
He also said that the company would not have employed him without the clause.
The authority heard that Mr Hall was given one week's notice of his dismissal and was told by way of a letter left on his desk.
Upon discovering the letter he requested a meeting at which he was told by Mr Smith that in his opinion he was not capable of doing the job.
ERA member Christine Hickey found that the 90-day trial clause was not valid and said Mr Smith did not comply with basic requirements of the Employment Relations Act when he terminated Mr Hall's employment.
"Mr Hall was not told of Mr Smith's concerns about his performance and had no opportunity to respond to those concerns or to improve his performance.
"The defects in the process were not minor and resulted in Mr Hall being treated unfairly.
"In the absence of a valid 90-day trial period provision a fair and reasonable employer could not have acted in the way SCC did and could not have made the decision to dismiss Mr Hall on performance grounds. Therefore, the dismissal was unjustified."
Ms Hickey ordered Mr Hall's former employer pay him $31,326 in lost wages, $7000 for humiliation, loss of dignity and injury to his feelings and $766 in reimbursement for variations he had to make to his work visa.
Mr Smith described the outcome as "bloody stink" and said the company would be appealing against it.
"That letter of offer that we gave to him when he was in the UK referred to an individual employment agreement.
"It said 'if you find the conditions of this letter and the attached employment agreement acceptable, please sign at the bottom of the letter' so he signed and accepted it, but didn't sign the actual contract.
"Even though he didn't sign the actual agreement, the letter referred the agreement and he accepted the conditions on the basis of the agreement."