A Queensland engineer who believes he is the love child of Prince Charles and the Duchess of Cornwall is facing a number of legal battles due to his claim.
Simon Dorante-Day is fighting for his job on two fronts and plans to file a case in the Family Court in an attempt to resolve his "royal issue".
The radio electrical engineer is suing Public Service Commission executive director Kurt Marsden, who made the decision to suspend him with pay 10 months ago.
Mr Dorante-Day has taken Mr Marsden to the Supreme Court in an attempt to get his job back.
The 52-year-old represented himself at the trial on Wednesday armed with folders, a clipboard and arguments which included the constitution and the Charter of the Commonwealth.
He told the court his "paternity issue" had influenced his suspension from work.
But the Supreme Court was told the executive had not taken that into account when deciding to suspend him, pending an investigation that was not disclosed to the court.
Mr Dorante-Day declined to cross-examine Mr Marsden, saying he was unprepared as he did not know Mr Marsden was available to be cross-examined.
He told the court that one of the reasons he was suspended was because his bosses thought he had threatened them in a phone call.
Mr Dorante-Day said they thought he said on the call that they were being watched by royal authorities.
"I never said that at all but of course, being a phone call, I don't here today have any proof of what was discussed, besides my wife's affidavit," he said.
He said his bosses brought up the "royal issue".
"The paternity issue had a lot of influence in the department, had a lot of effect in the department."
He went on to explain there had been a "workplace issue" in 2015 after he was late because he had "been on the phone to Buckingham Palace" until 4am one morning.
"I went to bed and turned off the phone and when I didn't go to work because I overslept they rang me up and didn't get an answer," he said.
"They then came to my house and knocked on the door, which they claim is HR policy. It wasn't."
Following this explanation, Justice Debra Mullins suggested he was going off on a tangent.
Lawyers representing the Crown said their case would largely rely on written submissions.
The court was told Mr Dorante-Day has previously filed proceedings relating to his paternity in the Federal Court.
Justice Mullins reserved her decision.
Outside court, Mr Dorante-Day told AAP he planned to take his "royal issue" claims to the Family Court when the case was resolved.
He said he also faced a concurrent work suspension which he planned to fight at the Queensland Industrial Relations Commission.
"I'm going back to the Family Court," Mr Dorante-Day said.
"As soon as this is done I will go and do that."
Australian Associated Press
