A workplace COVID-19 vaccination mandate is being fought in court after unvaccinated Hunter Valley mineworkers were stood down. 

Last month up to 80 employees at BHP Billiton's Mt Arthur coal mine were stood down after they could not provide evidence of their vaccination status.

BHP has said the number is now down to 35.

The main union representing coal miners, the CFMEU, is opposed to the mandate or so called 'Site Access Agreement' and said it was unlawful and unreasonable.

The union has taken BHP to the Fair Work Commission and its full bench has been tasked with making a decision.

It is deemed a 'seminal case', meaning it is capable of being being influential and important in terms of vaccinations within a workplace.

BHP's legal team has told the commission "the status quo is that health and safety controls must be complied with" and the company was obliged to protect its workforce.

Was consultation lacking?

The workers argue the vaccine mandate is unlawful because it was introduced without complying with consultation requirements in their employment agreement.

Two of the workers, who cannot be named,  gave evidence.

One of them described rarely accessing their company assigned email addresses, where vaccination advice was sent.

BHP told the court it sought feedback from staff via company emails sent to employees.

But when asked if he became aware of a broadcast email about vaccinations via his company account, he said he got his work emails on a personal account.

He said it was not until recently he got access to his BHP company email account.

BHP's lawyer rejected that, telling the commissioners the man had been given access years before now.

The second employee said  it was practice for communication matters to be sent on the BHP email address.

He said he got a vaccination update from the Mt Arthur leadership team on August 31 this year and said it was not his first such update.

But he said he was not sure when he got the first update.

He said in relation to the August 31 update he only read it weeks after it landed in his inbox.

He said after he read it there was little discussion with other workers.

"Did other workers at the mine initiate discussions with you about a proposal that BHP was actively assessing vaccination as a condition of entry," he was asked.

"It was spoken about informally, but I didn't have any answers because nothing had been communicated to me about it," he said.

BHP said word consultation not used but feedback sought

BHP's health safety representative was questioned in depth about consultation.

He acknowledged prior to the mandate was announced the word consultation was not used.

He was asked about so called 'talking points'. 

"I want to suggest to you that those talking points, didn't mention consultation," the union's lawyer asked.

"The use of the term (consultation), that appears correct," the health safety representative responded.

He was then asked if there was consultation in a sense in some other way.

"Yes through the conversations with the senior leader group," he said.

The health safety representative also agreed that in advice three days before the October 7 announcement, documents did not include the word 'mandatory'.

He previously said a decision on mandated vaccines was made on September 25, before workers were told.

The hearing continues on Thursday with a decision expected next month.