High Court backs sacking of BHP worker

A High Court decision to dismiss the appeal of a BHP Coal worker sacked for calling his colleagues "scabs" is a blow to freedom of expression, the mining union says.

BHP Coal worker Henk Doevendans was fired in 2012 for waving a sign that read "SCABS - no principles - no guts" during a strike outside the Saraji coal mine in central Queensland.

The mining company was ordered to re-hire the machinery operator after the Construction, Forestry, Mining and Energy Union successfully appealed his dismissal in the Federal Court.

However the order was overruled last December after an appeal to the full Federal Court.

The High Court on Thursday sided with the Federal Court decision to endorse his sacking, rejecting the union's argument that his behaviour was part of protected industrial action and he couldn't be sacked under the Fair Work Act.

BHP Coal has disputed whether his behaviour was protected by the workplace laws, comparing it to being sexist or racist to a colleague at work.

The CFMEU's mining and energy division's general secretary Andrew Vickers said the decision was a "blow to workers' rights, freedom of expression and participation in lawful industrial activity".

"The word 'scab' is of common and historical use in Australian industrial disputes - it's not a personal insult but a reflection of collective values," he said.

"We maintain our belief he was targeted for sacking not because he was holding a sign but because he was a union delegate."