Documents obtained by the Herald under the Official Information Act reveal the Government was already discussing a supervision regime for deportees last year - but that work stalled over issues including how it would be funded and a lack of information being provided by other countries.
Without the work progressing, criminals were deported to New Zealand this year with no monitoring or supervision regime in place.
In 2014, then-Justice Minister Judith Collins had indicated a preference for officials to develop further information about a supervision model based on release conditions, a February 12 briefing paper from Ministry of Justice officials to Ms Adams states.
"This work slowed in part due to uncertainty about the number of deportees, information required from other countries and the associated costs for justice sector agencies, particularly the Department of Corrections."
Labour's foreign affairs spokesman David Shearer said not progressing the work was a missed opportunity, and New Zealanders were put at risk as a result.
Even when Ms Adams started officials working anew on a monitoring regime, there was a lack of urgency and too much fiddling, he said.
"We should have said to the Australians, until we get the details, don't send them back ... we could have played it hard with the Australians if we wanted to, but we haven't."
But Ms Adams said the regime was developed as fast as possible, and working with Australia to access information was always a crucial precursor.
Labour had been in government for nine years and had not moved to ensure deportees were adequately supervised, Ms Adams said.
Richard Schmidt, the Ministry of Justice's general manager criminal justice policy, said that while work on the supervision regime slowed, related work progressed.
A register of deported offenders was established this year, as well as an information-sharing agreement with Australia - a "central component" in being able to develop a supervision regime.
"We can't be confident that a regime that was drafted in 2014, without knowing about the detail of the upcoming Australian law change, would adequately have responded to the particular circumstances that arose in relation to deportees from Australia, who form the vast majority of returning offenders."
Emails and documents released under the Official Information Act also detail the information received about those facing deportation.
As at May 31, Australia's Department of Immigration and Border Protection advised New Zealand officials that 585 New Zealanders were likely to have their visas cancelled for offences including:
• Assault - 121 (21 per cent)
• Theft, robbery and breaking-and-entering - 83 (14 per cent)
• Drug offences - 64 (11 per cent)
• Child sex offences, including pornography - 34 (6 per cent)
• Murder and manslaughter - 22 (4 per cent)
• Rape, sex offences - 16 (3 per cent)