There wasn’t much detail in Malcolm Turnbull’s launch of his asylum seeker policy this morning (“we will announce further details of our border protection policy closer to the election”), except that Temporary Protection Visas would be back under a Coalition Government.

It doesn’t quite solve the problem of those “but what would you do, Mr Turnbull?” questions, but gives them something to talk about for the time being.

Putting aside their humanitarian impact, a dispassionate look at TPVs suggests their main problem is they don’t work in preventing boat arrivals. In fact, they might encourage them.

And as last week’s events in the Indian Ocean demonstrate, preventing boat arrivals is a worthy policy goal, regardless of how you feel about asylum seekers.

The first point is that there is nothing inherently wrong with temporary protection, and it has been used effectively by Australia in the past to give shelter to people facing violence and dislocation. Some conflicts and humanitarian crises are semi-permanent, but others are of limited duration. Most of the more than 4,000 Kosovans into Australia in 1999 returned to their homeland once Serbian forces had been expelled, and large numbers of East Timorese people fleeing the brutality of Indonesian-backed militias also found temporary refuge here.

However, the Kosovans and the East Timorese were temporarily placed here under a special “Safe Haven Visa” category, not TPVs.

The TPV, introduced in 1999, was not about offering a temporary sanctuary, but about punishing people who applied for asylum in Australia, or who had spent more than a short period in another country, and thereby discouraging them. Asylum seekers who applied from outside Australia — i.e., in the language of the Howard Government, who didn’t “jump the queue” — received permanent protection visas.

It is unclear which type of visa the Liberals are planning to reintroduce. This morning, Turnbull said he would re-introduce a “non-permanent visa for asylum seekers who arrive without authorization” but also referred to it as a “safe haven visa” which would end if a holder’s source country was deemed safe, or convert to a permanent visa.

The Howard Government’s TPVs were distinguished from permanent protection visas not merely because of their limited duration — usually three years, with the possibility of renewal at the end of that period – but because holders could access fewer services and had fewer rights than permanent visa holders. TPV holders could only access a very limited number of social security benefits, were not eligible for Department of Immigration support services or language training, and couldn’t leave the country without losing their visa.

Refugee advocates argued that the temporary nature of the visa and the consequent uncertainty also caused psychological harm to holders.

Most of all, TPV holders had no right to family reunion which, coupled with a ban on international travel (if a TPV holder left the country, he or she couldn’t return), meant TPV holders were effectively barred from seeing their families again if they were overseas. Turnbull indicated this morning that his TPV category would similarly not permit family reunion.

This is the basis for the argument that the TPV regime encouraged families of TPV holders to attempt to reach Australia by boat, because there was otherwise no legal way to see their family member again unless they were later granted a permanent protection visa. That is why there were so many women and children aboard SIEV X, on which 288 women and children perished, along with 65 men, in October 2001.

And that is why the ALP committed to abolish the TPV before the 2007 election, and did so last year. The ALP, when Julia Gillard was shadow minister for Immigration, had initially supported TPVs.

Apart from encouraging TPV holders’ families, the TPV regime, which in terms of incentives should have discouraged asylum seekers from seeking to reach Australia, appeared not to work: there was a significant increase in boat arrivals after the introduction of the TPV in 1999, with boat arrivals nearly 50% higher in 2001. Clearly the TPV regime did not create a sufficiently harsh deterrent for those determined to make the dangerous journey by boat.

This was subsequently reinforced by the fact that the great majority — nearly 90% — of TPV holders were eventually given permanent protection visas. Asylum seekers — or the people smugglers who transported them — may have correctly guessed that once in Australia, even temporarily, they would be well-placed to secure permanent residency, despite the notional benefit of applying for the same from off-shore.

The visa proposed by Turnbull appears to accept this logic — it seems it would initially be temporary, but then convert to a permanent visa at its expiry if the holder’s country of origin was not deemed safe. That approach is sensible, and will minimise the harm caused to holders by uncertainty, but in doing so, it undermines any deterrent value of the TPV. It will be clear from the outset to asylum seekers and people smugglers that there’s still a secure path to a permanent visa through coming to Australia before applying for asylum.

All the evidence is that TPVs don’t do what they’re intended to do — encourage asylum seekers to apply from offshore — and may even encourage more boat arrivals of TPV holders’ families. Turnbull appears — much like the Government — to be caught between maintaining the rhetoric of a hardline against the boats and finding a humane policy that might actually accomplish that.