Elon Musk's X has policies to take down harmful content when it chooses but should not be allowed to overrule Australian law in deciding what can be viewed there, a lawyer for the cyber regulator told a hearing into video of a bishop being stabbed.

X, formerly Twitter, is fighting an order by the e-Safety Commissioner to remove 65 posts showing video of an Assyrian Christian bishop being knifed mid-sermon in Sydney last month, in what authorities called a terrorist attack.

"X says ... global removal is reasonable when X does it, because X wants to do it, but it becomes unreasonable when X is told to do it by the laws of Australia," Tim Begbie, the lawyer, told a hearing of the Federal Court, Australia's second-highest.

Other platforms, such as Meta, took down the content quickly when asked, he said, adding that X had policies to remove very harmful content, as responsible services did.

But X's opposition to global removal could not be right as it would determine the definition of "reasonable" within the terms of Australia's Online Safety Act, he added.

The company Musk bought in 2022, with a declared mission to save free speech, says it has blocked Australia from seeing the posts but refuses to remove them globally on the grounds that one country's rules should not control the internet.

Begbie said the dispute was not a debate about free speech but rather about the practicality of the Australian law that gives the regulator power to protect citizens from the most objectionable content.

Geoblocking Australians, the solution X offered, was ineffective because a quarter of the population used virtual private networks that disguise their locations, he added.

"Global removal in these circumstances is a reasonable step," he said. "It would achieve what parliament intended, which is no accessibility to end users in Australia."

Lawyers for X have yet to make their argument, but previously called the regulator's order an overreach of its jurisdiction, a contention Musk has repeated in posts on his website.

The one-day hearing continues.