An Adelaide man has lost a compensation claim against a market research company he claimed illegally trespassed on his property.

Key points: Adelaide man Dean Cosenza sued a market research company for going on his property without approval

Adelaide man Dean Cosenza sued a market research company for going on his property without approval He initially won compensation in the magistrates court after Roy Morgan failed to respond to his claim

He initially won compensation in the magistrates court after Roy Morgan failed to respond to his claim He lost a Supreme Court appeal against the judgment

It is the second time Woodville South resident Dean Cosenza has won a trespassing case that was later overturned on appeal.

Mr Cosenza will have to pay Roy Morgan Interviewing Services' legal costs after losing his latest Supreme Court appeal.

Mr Cosenza sought $100,000 compensation in the Adelaide Magistrates Court for the trespass that occurred in February 2017.

He claimed the interviewer "banging and ringing on the door in an unreasonable manner" caused him and his mother "much distress and harassment".

Mr Cosenza had a sign in his front yard saying: "Warning: Entry is Forbidden: Enter by Express Invitation Only: High Court Decision: Plenty v Dillon [1991] HCA 5".

The sign refers to a High Court case that decided people could revoke permission for police to be on their property.

Roy Morgan failed to turn up to the civil case and Mr Cosenza was awarded a default judgment, with compensation to be decided in a further hearing.

Mr Cosenza won a similar trespassing case against Origin Energy after the electricity company failed to respond to the claim.

An administrative error resulted in him being awarded the maximum $100,000 instead of another hearing being arranged to determine damages.

A magistrate overturned the order and a second case was settled out of court.

Interviewer had wife act on his behalf

Mr Cosenza's first magistrates court case against Roy Morgan was set aside after the company claimed it was not aware of the proceedings.

In a new hearing, Roy Morgan claimed it was not liable because its employee, Jay Thumar, had his wife, who is only named as Mrs Thumar in the judgment, act on his behalf without authorisation, and it was not liable for her actions.

It won the case and Mr Cosenza appealed to the Supreme Court.

Mr Thumar was fired after an investigation by Roy Morgan found people on the same street as Mr Cosenza had also been interviewed by his wife rather than him.

In a judgment handed down on Thursday, Supreme Court Justice Greg Parker dismissed the appeal, saying the magistrate was correct in setting aside the original case and denying Mr Cosenza's claim in the second hearing.

Mr Cosenza, a soccer player agent, declined to comment.

He runs a website selling "no trespassing" signs and kits explaining homeowners' property rights.