John Shakespeare Some of the letters dealt with Newstart, sickness and other payments going back six years, beyond when most people keep records, and way beyond the six months the Centrelink website asks people to keep pay slips. If they could get on to the right part of my.gov.au (which was difficult in the lead-up to Christmas) and if they entered the correct information, they were often still told they owed money, and sometimes told to pay it even if they disputed it in order to avoid debt collection. In a reversal of the usual onus of proof, they were guilty and sentenced until later proven innocent. Many are entirely innocent. An internal Centrelink check is said to have found that only 20 out of hundreds of cases reviewed are genuine debts. Social Services Minister Christian Porter uses a different metric to say that eight in every 10 letters has uncovered a legitimate debt. But they've done it by the equivalent of spamming, by sending out thousands of obviously wrong assessments in the hope of getting money while they are contested. They are assessments that never would have got past quality control had humans been in charge of the process, as they used to be until Centrelink put it in the hands of robots mid last year.

In a reversal of the usual onus of proof, they were guilty and sentenced until later proven innocent. It was a worthwhile aim. None of us should want either overpayments or underpayments. But the delivery was appalling. Morrison and Porter had promised all the P76 promised and somehow delivered what the P76 delivered. One of the wilder theories is that they intended to. By inflicting a faulty debt recovery system on the public, they wanted to persuade ignorant, scared and busy people to hand over money they didn't owe and dissuade others from ever applying for benefits again. A more likely explanation is that they didn't know what they were doing. Asked about the letters sent out by his department threatening a 10 per cent recovery fee, a surprised Human Services Minister Alan Tudge told the ABC: "A 10 per cent recovery fee is new to me, and I don't believe that does occur." Loading

But they might not have reckoned on the extent to which people can fight back. Many of those wrongly hit up have in the intervening years qualified as lawyers. They are talking about a class action. They are going to use the freedom of information process to document how robo-debt was set up and to get the medical and other records that the department already had but chose not to share with robo-debt. Tudge, Morrison and Porter could do worse than look beyond our shores to Michigan in the US. It backed down after sending out tens of thousands of robo-debt notices in error and announced that in future assessments would be overseen by human beings.