“The Australians have agreements with Papua New Guinea and Nauru to transfer those arriving illegally for processing. This was successful in reducing illegal maritime arrivals.”

That’s the claim from the UK Home Office factsheet on the government’s plans to send some asylum seekers to Rwanda.

The UK policy is that “every person who comes to the UK illegally, or by dangerous or unnecessary methods from safe countries – including those arriving by small boats, hidden in the back of lorries and found in the UK without leave – will be considered for relocation to Rwanda.”

So, did the Australian offshore asylum system reduce dangerous sea crossings?

Let’s take a look.

What is offshore asylum processing?

Like the UK, Australia has a history of people – particularly those fleeing war and persecution – attempting to reach the country unofficially by boat.

The term “asylum seeker” refers to someone who is asking for safety in another country. If they are granted asylum, they are given refugee status.

Under normal circumstances, whether someone receives that status is up to the country they’ve arrived in. Offshore processing is when asylum seekers are sent to another nation to have their claims heard.

In September 2012, the Australian government restarted a policy that had previously been in place in the early 2000s: sending some people who came to the country by sea for asylum processing in Papua New Guinea and Nauru.

In July 2013, newly re-elected prime minister Kevin Rudd expanded the scheme to everyone reaching the country by unofficial boat and declared that no-one who arrived by this route would ever be allowed to resettle in Australia.

Did Australia’s offshore asylum scheme reduce ‘illegal maritime arrivals’?

At first glance, the answer appears to be yes. The number of people arriving by boat on Australian shores is now significantly lower than it was in the years before offshoring was introduced.

But on closer inspection, the picture is less clear.

In the year after offshore processing began, the number of arrivals did not decline – it increased. Some 25,173 people arrived by boat between July 2012 and July 2013 – three times more than the number who crossed in the previous 12 months. (We’re using the Australian Library of Parliament’s July to July figures as this is the structure of the Australian financial year).

Other factors at play?

It’s only in 2014 that we start to see a significant fall. That year, the total number of maritime arrivals was 157. The following year, it was zero.

It’s hard to say for certain what brought this about, but one possibility is the ‘turnback’ and ‘takeback’ policies. The Australian military began escorting small boats to the edge of its territorial waters (turnbacks), and the authorities started working with other nations to return people who’d reached Australian shores (takebacks).

The first turnbacks – part of Operation Sovereign Borders – began on 17 December 2013. This coincides more closely with the drop in boat arrivals than the introduction of the offshoring policy in 2012.

And it’s not just the number of people reaching Australia by boat that fell – FactCheck analysis of Australian Library of Parliament data shows the number of people attempting the crossing declined significantly too after 2014. (Although we should say that this dataset may undercount the true number of people attempting the crossing).

This is important because part of the stated rationale for the policy was to deter people from making the dangerous journey in the first place. (Though as this expert testimony to the UK parliament notes, the practice of escorting boats out of Australian waters is hardly risk-free for asylum seekers).

You might be thinking: could the decline in boat arrivals be thanks to Kevin Rudd’s toughening of the offshore regime in July 2013?

Again, it’s hard to say. Madeline Gleeson, senior research fellow at the Kaldor Centre for International Refugee Law at UNSW Sydney, tells FactCheck that the short time between that announcement and the beginning of turnbacks “prevents a straightforward line of causation to the drop in boat arrival numbers.” In other words, we can’t separate out which policy was the true cause.

“However,” she says, “there are other persuasive indications that the resettlement issue [i.e. the toughening of offshoring] on its own was not a deterrent.”

Using official figures, Ms Gleeson and her colleagues found that 1,241 people either reached Australia or were turned back between September and December 2013. At this point, the offshore processing system had been toughened, but the policy of turnbacks and takebacks was not yet fully operational. If it was the offshore toughening that caused the decline, we’d expect to see a major fall during that period. In fact, more people reached or attempted to reach Australia in those three months than made the journey in the whole of 2014. This further suggests that turnbacks and takebacks were more important than the offshore regime.

But we should be clear that even this correlation is not proof that it was the turnbacks and takebacks that caused the decline in numbers.

Andreas Schloenhardt, professor of criminal law at the University of Queensland, told FactCheck to “keep in mind that the Australian Government implemented a suite of measures, which makes it difficult to point to the specific effect of any one of them.”

So, we have some possible alternative explanations for the decline in boat arrivals, though none of them are proven.

But let’s take a step back. It’s for the UK government to demonstrate that its claim that offshore processing caused the reduction in people crossing by boat is correct.

To do that, it would have to show a correlation between the two events (boat crossings fell after the policy was introduced) and that other plausible explanations had been ruled out. The evidence that the two events are correlated is, as we’ve seen, patchy. And there are other explanations – like the introduction of turnbacks – that have not been ruled out and are more closely correlated with the fall in boat arrivals.

Prof Schloenhardt told FactCheck that, in his view, the UK government’s assertion is “overly simplistic” and “ignores that a myriad of measures and other factors were (and always will be) at play.”

What lessons for the UK?

Unlike the Australian scheme, people sent to Rwanda by the UK government would not be detained there. Once they arrive, they are free to leave or to seek asylum in the country.

The government says: “People will have all their needs looked after while their asylum claims are being considered in Rwanda […] Those relocated will be given a generous support package, including up to five years of training, accommodation and healthcare.”

This may help avoid a repetition of the many documented problems caused by Australia’s detention centres. The regime has seen hundreds of people – including children – detained for a year on average in overcrowded and unhygienic detention centres in partner countries. Some people have been trapped in the centres for years.

Still, critics of the UK scheme have raised concerns that Rwanda’s asylum system might not be able to cope with a large volume of applications and warn that some of those taken to the country could be traumatised by the experience.

The Home Office was keen to stress the differences between the UK and Australian schemes and disputed the suggestion that the UK’s Rwanda policy constitutes asylum offshoring, arguing instead that it is a “migration and economic partnership”.

We put it to the Home Office that it was incorrect to say that Australia’s arrangements with Papua New Guinea and Nauru caused a reduction in boat arrivals because the correlation wasn’t clear, and the turnback and takeback policy seemed a more likely explanation. A spokesperson told FactCheck: “We do not accept these claims at all. Our world-leading partnership with Rwanda is a fundamental part of our strategy, underpinned by measures in the Nationality and Borders Act, to overhaul the broken asylum system and drive down illegal migration.”

FactCheck verdict

In a factsheet on the UK policy to send some asylum seekers to Rwanda, the government says “the Australians have agreements with Papua New Guinea and Nauru to transfer those arriving illegally for processing. This was successful in reducing illegal maritime arrivals.”

But the evidence that asylum offshoring caused the reduction in boat arrivals is patchy.

One alternative explanation could be the Australian military’s policy of turning back unofficial boats, which began in December 2013.

Experts warn that it is difficult to measure the effects of any individual scheme as Australia introduced several asylum policies within months of each other.