Israel Folau is claiming Rugby Australia has enforced “an unreasonable restraint of trade”, according to a statement of claim lodged with the Federal Circuit Court of Australia.

Folau, a devout Christian, had his contract terminated for a “high-level breach” after he posted “hell awaits drunks, homosexuals, adulterers, liars, fornicators, thieves, atheists and idolaters” on Instagram.

Rugby Australia and Folau failed to reach a settlement in June over the full-back’s sacking and an unfair dismissal case began in court earlier this month.

A statement of claim published by the Federal Circuit Court showed Folau is stating his inability to play international rugby due to the termination of his contract constitutes “unreasonable restraint”, referring to “public policy”.

It also suggests the direction of a tribunal was “void” and there was an “absence of any valid finding”.

A section of the 26-page document reads: “The decision of the tribunal that termination of the player contract was the appropriate sanction to be imposed, and its direction to that effect, has the consequence that Mr Folau can no longer play rugby union at an international level [because he is only eligible to play for the Wallabies] or an Australian team in the Super Rugby competition and is therefore an unreasonable restraint of trade, contrary to public policy, and void.

“By reason of the decision and subsequent direction of the tribunal being void and of no effect, it was a breach of the player contract for Rugby Australia and Rugby NSW to terminate the player contract in the absence of any valid finding by the tribunal.”

Another part of the statement adds: “It is injurious and inimical to the public interest, and therefore against public policy, for a condition in a contract of employment to allow an employer to prohibit an employee, in their own time, from having or adopting any religion or belief, manifesting their religion or belief or imparting or sharing religious information and ideas, provided that the employee otherwise acts lawfully.

“Insofar as any term of the player contract, including any term of the code of conduct, prohibited Mr Folau, in his own time, from manifesting his religion or belief or from imparting or sharing religious information and ideas, provided he acted lawfully, the term – to the extent that it otherwise would have had such an operation and effect – was against public policy and therefore void at law and of no effect.

“In the premises, under the player contract, Mr Folau was free, in his own time, to manifest his religion or belief or to impart or share religious information and ideas, provided he acted lawfully, and as a consequence, the social media posts were not a breach of the player contract by Mr Folau.”

In an open letter to Rugby Australia members in June, Rugby Australia chief executive Raelene Castle wrote: “I want to make clear that RA has acted with complete professionalism and integrity at all times through the process by which Israel was found, by an independent three-member tribunal panel, to have made multiple, serious breaches of the professional players code of conduct.

“This is an employment matter and does not concern his religious beliefs or his ability to express them freely. If some of you follow Israel’s social accounts, you will have noticed he has posted religious material freely and openly over the last few years.”

The case will go to mediation in December but, if a resolution is not found, the parties could face trial in February.