Reuters reported, quoting three people who had been told about the case, that the proceedings were taking place in a federal court in California under seal so that no filings were accessible by the public.

In Australia, there would be no need for the case to be under seal, because under the draft law, issued on Tuesday morning for public comment, such matters are not meant to be made public, with big fines for anyone who makes mention of it.

Details of the US case were published by Reuters after a hearing on Tuesday regarding a government move to hold Facebook in contempt of court for refusing to provide the contents of the voice conversation.

The US Government is attempting to force Facebook to rewrite the Messenger software so that it can gain access to the suspect's voice conversation which is encrypted from end-to-end.

A similar situation arose in 2016, when the FBI went after Apple in a bid to obtain the data on an iPhone 5C which belonged to one of two terrorists who had been involved in an attack in San Bernardino, California, in December 2015.

The FBI took Apple to court, demanding that the company rewrite its iOS operating system in order that the agency could gain access to the data on the iPhone.

As part of the evidence that Apple presented to the court to show that this was a Herculean task, was a document written by its user privacy manager Erik Neuenschwander, detailing exactly how difficult and expensive it would be for the company to meet the FBI's demands.

Neuenschwander's document pointed out that even if Apple went through all the twists and turns he listed, there was no guarantee that the result would be what the FBI wanted.

The case ended before it could come up before a judge, with the FBI saying it had managed to gain access to the data by paying an external contractor to hack the device.

In the current case, Facebook has told the court that since Messenger calls are encrypted end-to-end, only the two parties concerned have access to the conversation. The company says it can only meet the government's demand it it rewrites the application to remove encryption or else hacks into either user's account.

In 2006, a US federal appeals court in Washington DC, made a ruling that law which makes it mandatory for telephone companies to enable police eavesdropping, also applies to some big companies that offer VoIP, including cable and other broadband carriers servicing homes.

But Al Gidari, a director of privacy at Stanford University Law School’s Centre for Internet and Society, told Reuters that officials had not made a bid to extend the law to apps that were not tightly tied to existing phone infrastructure.

He insists that messaging platform do not come under the purview of this law.