Australia’s world-first teen social media ban was “ill thought out” and amounted to a “profound ‌restriction on political debate”, a lawyer for messaging platform Reddit told the country’s top court in the first legal challenge to the law.

Reddit and a libertarian advocacy group have gone to the High Court to contest the Australian law, which bans large social media platforms from letting under-16s have an account and took effect ​in late 2025 amid support from parents and opposition from the tech firms.

The plaintiffs said the law should be declared invalid ​because it violates an implied freedom of political expression in the country’s constitution.

Reddit added that the law ⁠should not apply to it anyway because it does not have some features that are central to social media, including a reliance on ​friend networks.

A successful challenge could usher in more opposition from affected companies and slow a global uptake of similar policies as lawmakers from Britain ​to Malaysia roll out the measures in an effort to protect youth mental and physical health.

The Australian government and its communications minister Anika Wells, a named defendant, have said they will defend the law.

Addressing the court, Perry Herzfeld, for Reddit, said barring under-16s from holding social media accounts stopped them from creating or responding ​to content on what he called the most important means of communication in the modern world.

“That is a very profound restriction on political debate ​in Australia,” Herzfeld told the seven-judge panel.

“There is a very substantial restriction on what young people can now do.”

Reddit agreed with Australia’s harm-minimisation aim but the ‌law failed ⁠to achieve it, Herzfeld said, terming the legislation “ill thought out” and “inept” since it did not call for any specific measure to keep out minors and failed to restrict other online services where cyberbullying took place, such as gaming websites.

While social media content could typically only be created or commented on by logged-in account-holders, vast amounts of material were visible to people with no account, he said.

Speaking outside the court, communications ⁠minister Wells ​said she would respect its decision, which cannot be appealed, but would fight the challenge.

“We ​are here to defend a fundamental tenet of Australian democracy, which is an Australian’s right, and particularly an Australian child’s right, to be free from harm,” Wells said.

“We seek ​to defend that from sustained ideological attack.”