The industrial umpire this week upheld a January ruling that the BHP Billiton subsidiary, which operates Appin Mine north-west of Wollongong, had not bargained in good faith towards a new enterprise agreement.

The company is reviewing the decision and said it remained "open for legal review and analysis", according to Illawarra Coal head of external affairs John Brannon.

However, Association of Professional Engineers, Scientists and Managers Australia (APESMA) collieries division director Catherine Bolger described it as a landmark decision.

"I think the ruling has significant implications because it's the first decision that really looks at what is 'surface bargaining' and whether it is good enough to simply sit at the bargaining table and just respond with reasons against something rather than putting forward a positive proposal," she said.

APESMA represents administrative assistants, accountants, ventilation, training and store officers and some managers.

At least 12 bargaining meetings were held between the company and the union between August 2010 and August 2011, however an impasse was reached which, according to the union, arose because Illawarra Coal was never interested in finalising an agreement.

Illawarra Coal said the stalemate was caused by the union refusing to change its position on various issues.

In January, Fair Work Australia found the company was not bargaining in good faith.

A subsequent appeal by Illawarra Coal led to Thursday's decision.

In determining the appeal, FWA did remove a previous order for the company to provide the union with certain financial information - a decision Mr Brannon said was welcomed by Illawarra Coal.