A Melbourne painting and decorating company, and its director, have been fined $20,000 after telling a worker he could not work at particular construction sites unless he joined the CFMEU.

Arteam director Michael Hanna admitted to sending a text message to workers in March 2014 stating that they must have valid union memberships before starting work at two Melbourne projects.

When questioned whether union membership was compulsory, Mr Hanna told the worker he would not be allowed to work on the Tullamarine Quest Apartments site unless he was a paid-up member of the CFMEU.

He also allegedly told the worker that the CFMEU could “close” the site and prevent others from working if he remained on-site without paying the membership fees.

The worker left and did not return to the site.

In handing down his penalty on Wednesday, Federal Court judge Richard Tracey said he found evidence of a culture within the construction industry that accepted compulsory union membership – despite freedom of association laws.

“Despite working in the construction industry for some 11 years, Mr Hanna had remained ignorant about the laws,” Judge Tracey said.

“Mr Hanna had become immersed in the culture of at least some commercial construction sites on which compulsory union membership was accepted by both employers and employees.”

Mr Hanna and Arteam were fined $2400 and $17,600, respectively.

The CFMEU and one of it’s representatives, Godwin Farrugia, are also listed as respondents in this matter but are defending allegations against them and a trial will take place in 2017.