The federal court has given a green light to pianist Jayson Gillham to sue the Melbourne Symphony Orchestra, and Chief Justice Debra Mortimer ordered the case to be tried.

In March, the MSO tried to throw away Gilham's case, believing that the pianist was not an employee, but a free contractor, and therefore neither the Fair Work Act nor the Victoria's Equal Opportunity Act would apply.

The legal team of pianists led by senior legal counsel Sheryn Omeri believes that under the Victoria's Equal Opportunity Act, the so-called discrimination of MSO is based on political beliefs or activities.

On Thursday, a federal court ruled against the MSO and ordered a trial. Mortimer says she is “The case without convincing the applicant has no reasonable prospect of success” and agrees that the relationship between the pianist and the orchestra is protected by workplace laws.

Gillham sued MSO at a cancelled Melbourne concert signed on August 15, claiming it was an attempt to silence his stance on his conflict in Gaza.

During a performance at the Ivaki Auditorium on the South Bank four days ago, Gillham played a short work titled "Witnesses" composed of Australian multimedia artist Connor D'Netto, which is specifically aimed at journalists who died in the Gaza conflict.

The pianist addressed the audience while introducing the work, saying more than 100 Palestinian journalists were killed, and in the conflict, the journalist’s target was war crimes under international law.

When announcing the decision to cancel the August 15 concert, an MSO email sent to customers said that Gillham made his personal comments “not seeking approval or sanctions from the MSO.”

"MSOs will not tolerate using our stage as a platform to express personal opinions," the email said.

The MSO then issued a statement denied that Gillham was discriminated against for his political views, saying that the operational management was in response to the artist’s comments on the stage, “not and not about freedom of speech.”

In a statement issued after the lawsuit was announced in October, Gillham said the pianist said the MSO's actions were "part of a disturbing trend in silence, which speaks to disturbing truths."

"This situation is not limited to art freedom; it is at the heart of our right to freedom of speech and the role of art in solving important social problems," he said in the statement.

Less than two weeks after the controversy broke out, MSO musicians reportedly had no confidence in the organization's managing director Sophie Galaise, who resigned in late August.

Galaise stopped the defendants in a legal lawsuit against the MSO in March, and Gillham reached a confidential settlement with the former MSO boss a few days before the group tried to dismiss the lawsuit in federal court.