Should Brenton Tarrant be returned to Australia? Certainly that is the view of Winston Peters. Judith Collins has another view, telling the Sydney Morning Herald last week she feared "a flood of criminals in Australian jails could be sent the other way".
Both Jacinda Ardern and Scott Morrison have been more circumspect. New Zealand has yet to make any formal request to Australia regarding Tarrant. All Morrison has said is that he is open to considering a request.
Not only are Tarrant's crimes without precedent, so is his life sentence without parole. As it stands, he will live out the remainder of his natural life in New Zealand prisons.
Tarrant was born and raised in Australia and lived in Grafton, New South Wales, before moving to New Zealand. Not since Hobart man Martin Bryant killed 35 people during the 1996 Port Arthur terror attacks has an Australian been responsible for mass murder.
Australia has no legal obligations to take back Tarrant. There is no requirement that Australians be automatically returned home once a foreign court has handed down a sentence. Only once an Australian's foreign prison term has ended will they be deported. Peters has observed that at present the only way Tarrant will be returned to Australia is in a body bag on his death.
Australia does have in place legal mechanisms for the transfer of foreign prisoners from Australia, and the return of Australians from overseas prisoners under the International Transfer of Prisoners Scheme. There are currently 70 participating countries in the scheme, with the legal framework resting under either the Council of Europe Convention on the Transfer of Sentenced Persons or separate bilateral treaties. In 2018-19, 34 transfers occurred under these processes.
Australia sees benefits in prisoner transfer because it improves prospects for rehabilitation, facilitates family contact, and meets public expectations that Australians imprisoned overseas will serve their time in Australia. There is also a cost efficiency as foreign prisoners are no longer a burden on Australia.
However, New Zealand is not a party to the Council of Europe scheme and has no bilateral treaty with Australia, there is no legal process for Tarrant's return to Australia.
Suggestions that Tarrant could be extradited or deported to Australia fail to appreciate those processes are also not available while a life prison sentence is being served.
The lack of a transtasman general prisoner transfer arrangement is a curious exception in what is otherwise a very close legal and political relationship. If New Zealand really wished to resolve Tarrant's situation, it could simply sign on to the Council of Europe scheme.
However, given the unique circumstances of the Tarrant case, there is probably a stronger case for a bespoke arrangement. The sentence handed down against Tarrant really does mean life. Unless there arises some unforeseen circumstances, the 29-year-old can be expected to live up to 40 to 50 years.
Australia has experience in negotiating special prisoner transfers. The most prominent was the 2007 agreement with the United States for the return of David Hicks after he was convicted on terrorist related charges. Hicks returned to Australia and served out the remaining nine months of his sentence in Adelaide's Yatala Prison. Australia also sought to negotiate the return from Indonesia of Schapelle Corby after her conviction on drugs charges in Bali. However, Indonesia was not prepared to permit convicted drug smugglers to be included in any separate agreement with Australia and Corby served out her sentence in Bali.
Given the postponed New Zealand election, movement on Tarrant's case is unlikely until later in 2020 or early in 2021. Australia would probably not be attracted to an arrangement that only dealt with Tarrant given the significant costs associated with securing him in an Australian prison for life.
Canberra would more likely favour a bilateral treaty arrangement to facilitate transferring New Zealand prisoners from Australia. A transtasman prisoner swap deal would be mutually beneficial to both sides. Tarrant would be returned to Australia while Kiwis would be sent back across the ditch. Importantly, the floodgates would not be opened on the return of Kiwi prisoners.
Tarrant has had a relatively low profile in Australia. Nevertheless, the Morrison government may be open to negotiating a longer term prisoner transfer deal as a means to resolving some ongoing issues in the transtasman relationship.
• Donald R. Rothwell is Professor of International Law at the ANU College of Law, Australian National University.