Hassein Halloum travelled from the suburb of Dallas to Wangaratta on Thursday morning, just hours after new laws came into effect requiring people from those areas to stay home unless for essential purposes.

He was a man originally from Lebanon who spoke little English and did not realise he was not meant to leave home.

Attending court could be considered essential travel, but a video link from Melbourne would have been available if requested.

Outdated police documents showed Halloum had previously lived in a different suburb in Melbourne that was not a hot spot.

He fronted court to plead guilty to a charge of possessing proceeds of crime - selling illegal tobacco as an employee of Raneen Gift Shop.

It was only after the case had finished that his lawyer William Barker realised Halloum actually lived in Dallas.

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Mr Barker returned to the court at about 11am to inform Magistrate Ian Watkins of what had happened.

Halloum had already left the building after his case finished to return home.

It is understood he was not showing any symptoms of being sick and said he had not come into contact with anyone who had coronavirus, but had not been tested himself.

He was not fined by police before he left.

The court clerk who had direct contact with Halloum, passing him a clipboard with documents to sign, and the police prosecutor who spoke directly to him were immediately sent home to self-isolate.

About 20 more people in the courthouse - including staff, police, security, lawyers and media - were told to wait inside the building as they tried to work out protocol for the new laws.

Advice from the Department of Health and Human Services was initially that people did not need to self-isolate, but that later changed.

A DHHS worker who attended the courthouse, but stayed outside at a safe distance, recommended anyone who was inside with the man from the hot spot go home and isolate, then get tested for coronavirus in a few days.

Halloum and his lawyer were also advised to have a test.

The courthouse was closed from lunchtime to allow it to be thoroughly cleaned, including door handles and chairs in both the courtroom and waiting foyer, and the front counter where Halloum may have had contact.

Halloum was earlier placed on a good behaviour bond with the condition to pay $500 to the court fund for his role in selling the illegal tobacco.

Prosecutor Senior Constable Stuart Prichard told the court that officers raided Raneen Gift Shop in Wangaratta's Murphy Street on May 17, 2019 and found 29,960 illegal cigarettes weighing 40 kilograms.

"The tobacco does not have the appearance of legal tobacco products," he said.

"The tobacco was being sold by the accused at a much reduced price compared to other tobacco products."

The packages did not use known brand names of other cigarettes sold in Victoria and did not have the required health warnings.

"He stated he did not know where the tobacco came from or who owned the business," Senior Constable Prichard said.

Mr Watkins said he accepted Halloum's role was just the retail worker and he had no criminal history.

"What you have done in particular has deprived the Commonwealth of excise duty, money that would have otherwise been spent on other community purposes," he said.

"It's a serious matter."