Israel Folau says Rugby Australia's termination of his playing contract over a homophobic social media post is an "unreasonable restraint of trade".

The former Wallabies star and his legal team lodged a 26-page statement with the Federal Circuit Court this week, details of which were released on Thursday.

Folau is seeking $10million Australia dollars in damages, an apology and reinstatement from his former employers Rugby Australia and New South Wales Waratahs.

Rugby Australia said the homophobic post, Folau's second in two years, breached its code of conduct.

But Folau, 30, said the posts were "substantially unrelated" to rugby, and the termination of his contract was against the public interest for employees to be able to express religious beliefs in their own time.

"Mr. Folau can no longer play rugby union at an international level ... and (it) is therefore an unreasonable restraint of trade, contrary to public policy and void," the court document said.

"Mr Folau is a devout Christian, which the parties well knew at the time they entered into the Player Contract.

"He maintained social media accounts, not for the purpose connected to his employment as a rugby player, but primarily for the purpose of lawfully communicating religious content. He did this because of his religious faith, which goes to the very essence of his personhood.

"In his own time, Mr Folau uploaded some religious content on his social media accounts, as was his usual practice.

"There was nothing unlawful about his conduct, which was a manifestation of his religion and consistent with his freedom of religious expression."

Folau's case will be heard over three to five days in February 2020 unless the matter can be settled through court-directed mediation in December.