The national construction watchdog has spent thousands of dollars on what a federal judge has described as a "storm in a tea cup" over two mates having a cuppa at a Melbourne worksite.

Federal Court judge Anthony North on Monday dismissed a complaint by the Australian Building and Construction Commission, who had accused the CFMEU and officials Mark Travers and Adam Hall of breaching workplace laws.

Justice North described the case as “excitare fluctus in simpulo” – a Latin expression by Roman writer Cicero which means “storm in a tea cup”.

The ABCC alleged the pair broke the law after they entered a construction site at Melbourne Airport in 2014 to “have a cuppa and say hello” to a friend.

Travers, accompanied by Hall, had popped into the worksite operated by McConnell Dowell to see a friend who was also a union representative.

The men talked about their recent trips interstate and four-wheel driving over a cup of tea for about 20 minutes before a project manager told the CFMEU officials to leave, or he would call the police.

The manager said the pair did not have right of entry because they had failed to give 24 hours’ notice, as required for union visits under workplace laws.

But the pair explained they had gone to the site for a social visit so Travers could say hello to a friend.

The project manager later gave evidence that Travers and Hall had an “incredulous or surprised look on their face” in response to the request.

He also said their visit had not given any cause for concern, but he was following orders from management.

Justice North said the evidence points to “a wholly social visit” by the union officials.

The judge also found there were no existing safety issues at the time of the visit.

Two hearings were held about the case in December 2016 and March 2017 before Justice North handed down his 16-page judgment on Monday.

By Jacqueline Le