Many people, politicians included, tell lies. That does not make lying right. The former Scottish secretary Alistair Carmichael denied leaking a memo to the Daily Telegraph in April. An inquiry reported last week that Mr Carmichael had in fact authorised his special adviser to leak it. Mr Carmichael’s lie should be condemned. It was a serious error of judgment and his reputation is damaged. He has apologised and has given up his ministerial severance pay. Mr Carmichael is now facing calls to resign and may face a recall election in his Orkney and Shetland constituency if opponents get their way.

It is the lying that is wrong, not the leaking. Almost all politicians leak to the press. The government has already leaked the contents of much of Wednesday’s Queen’s speech. In a few weeks’ time the Treasury will be leaking the July budget. Like all media, the Guardian often gets leaks from ministers, officials and whistleblowers on matters of great public interest. Many are rightly published. The public would be astounded if they were not.

The memo that came across Mr Carmichael’s desk was unquestionably a matter of public interest. It said that the Scottish nationalist leader, Nicola Sturgeon, had told the French ambassador in March that she would “rather see” David Cameron than Ed Miliband as prime minister. This was at odds with the SNP leader’s public claims that she opposed a Tory government and would work with Labour. Both Ms Sturgeon and the ambassador subsequently denied that this is what the Scottish first minister said. Yet, at the time, the official who wrote the memo accurately recorded what he thought he had heard. It is obvious, given the election campaign, why Mr Carmichael’s team would have been so tempted to leak it.

The saintly can criticise Mr Carmichael for leaking. But it would be hypocritical for the media to condemn him for it. His fault was to lie and be found out. Should he consider his position? Yes, he should. Should he resign? Not so easy – but not at this stage. Mr Carmichael has not been charged with or convicted of a crime. Nor has he been censured by the parliamentary standards watchdog.

The former Lib Dem minister undoubtedly made an error he now regrets. But he is hardly the first politician to do that. Recall, in this context, Ms Sturgeon’s sensible words when she was under fire over the Abdul Rauf affair in 2010. She said her experiences “have made me wonder whether a more general willingness to allow each other space to reflect on honest mistakes, admit where we’ve got things wrong and learn lessons would be much better for our politics than the instant rush to judgment that all of us, me included, so often rush to”.

To dub Mr Carmichael’s actions an honest mistake would be generous. Yet Ms Sturgeon’s wider point still holds. The SNP’s hue and cry against Mr Carmichael may seem legitimate. It is also very self-serving. It is far from obvious that, as Ms Sturgeon put it, it is “better for our politics”. Like everywhere else, Scotland needs pluralism not a one-party culture. Mr Carmichael’s future hangs in the balance, but he and his constituents must decide his fate, not his opponents.