Dr Renwick held two days of hearings in Canberra on Thursday and Friday last week, meeting representatives of both government and industry.
There are three ways listed in the legislation by which law enforcement can get industry to aid in breaking encryption.
A technical assistance request or TAR allows for voluntary help by a company; its staff will be given civil immunity from prosecution.
Finally, a technical capability notice or TCN can be issued by the Attorney-General at the request of an interception agency. This will have to be also approved by the Communications Minister and will force a company to help law enforcement, by building functionality.
However a TCN cannot demand the decryption of information or removal of electronic protection in any system.
Dr Renwick said that what he had heard from technology companies was that using the AAT would give them more confidence in the process. To this end, he backed the addition of some technically qualified people to the AAT as part-time members.
He also suggested that a better definition was needed for the term "systemic weakness", adding that this would sit better within the text of law itself.
The encryption law, known as the Telecommunications and Other Legislation Amendment (Assistance and Access) Bill 2018, was passed on 6 December 2018.
A review was instituted by the Parliamentary Joint Committee on Intelligence and Security as soon as the bill was passed, with a reporting date of 3 April 2019. It was expected to make changes that would provide some solace to the technology industry.
But the panel then put off taking any decision, instead asking Dr Renwick to review the law and report back by 1 March 2020.
In October 2019, Dr Renwick said he was extending the date for submissions to his review until 1 November. At the time he made this announcement, just 15 submissions had been received.
The date for his report to the PJCIS is now the end of June; the PJCIS will then issue its report by the end of September. Only after that will the government look at any changes to the law.
Among those who fronted the inquiry over the two days were the ASIO, the NSW Independent Commission Against Corruption, the Law Enforcement Conduct Commission of NSW, the Human Rights Commission, Internet Australia, Electronic Frontiers Australia, Atlassian, Access Now, Mozilla Corporation, the Communications Alliance, Ai Group, AIIA, AMTA, DIGI & ITPA, AustCyber, Law Council of Australia, The Allens Hub for Technology, Law & Innovation, the South Australian Independent Commissioner Against Corruption, BSA | The Software Alliance, the Australian Federal Police and the Department of Home Affairs.