Yes, repetitively posting false statements that someone is...

Yes, repetitively posting false statements that someone is mentally ill with the intent to discredit them is illegal in Australia. This could potentially fall under several areas of law, including defamation, harassment, and cyberbullying.

1. **Defamation**: If the statements harm the person's reputation by making false claims, the affected individual could potentially sue for defamation. Defamation in Australia is governed by state laws and can result in significant legal penalties.

2. **Harassment and Cyberbullying**: Repeatedly making such posts could be considered harassment or cyberbullying, which are also illegal. The Enhancing Online Safety Act 2015, for example, provides a legal framework for dealing with cyberbullying and online harassment.

3. **Mental Health Act**: In some cases, making false claims about someone's mental health could also violate provisions of the Mental Health Act, especially if it leads to unwarranted stigma or discrimination against the individual.

If you or someone else is being targeted in this manner, it is advisable to seek legal counsel to explore the appropriate steps to take, which may include filing a complaint with the relevant authorities or seeking an injunction to stop the harmful behavior.