Australia's world-first teen social media ban was a modest, non-partisan and justified curb on political expression, a lawyer for the government told the top court on Wednesday, rejecting a legal challenge by Reddit. Nearly a year since Australia banned large social media platforms from allowing under-16s to hold accounts, messaging platform Reddit and a libertarian advocacy group have sought to invalidate the law on grounds that it violates constitutionally protected speech. The government is defending the law, calling it a necessary harm minimisation measure. A win for the plaintiffs would be a major setback not just for Australia but for lawmakers around the world who followed with similar measures in what has become a global movement to protect child physical and mental health in the digital age. After a lawyer for Reddit told the court the law's imposition on free speech for minors was disproportionate to the benefits of keeping them off social media, Stephen Lloyd, for the government, said the ban was a relatively minor measure with proven positive effects. "The burden is indirect and modest in extent," Lloyd told the court's seven-judge panel on the second day of hearings. Read: Australia introduces digital safety bill allowing users to switch off social media algorithms The law "incrementally" reduced children's ability to send and receive content online, while they could still view some content without an account, he added, noting it was "viewpoint neutral" so did not target any particular type of political expression. Under the law, children and caregivers face no punishment but platforms can be fined up to A$99 million ($68.97 million) for systemic noncompliance. So far, multiple studies including by Australian regulator the eSafety Commissioner have found that most of the country's under-16s still use social media, and the government has said it is preparing an enforcement lawsuit. On Wednesday, Lloyd said it was unclear if noncompliance was the result of weaknesses in age assurance technology or platforms' failure to implement it, but added that the law would contribute to the government's child protection aims regardless. The hearing has been adjourned to a date to be decided, when the judges are expected to give a ruling.