Leader comment:

It is clear that the SNP’s remarkable performance in the General Election campaign had the major parties rattled, and long before any results confirmed the party’s new political dominance. That is no doubt why then Scottish Secretary Alistair Carmichael agreed to the release of the now notorious “Nikileaks” memo, which suggested Nicola Sturgeon had told French ambassador Sylvie Bermann that she would prefer David Cameron to win the general election.

That decision has left his reputation badly damaged, perhaps irreparably so. The story (untrue) was published by the Daily Telegraph without seeking a response from the SNP leader and promptly collapsed as Ms Bermann denied such a discussion had been part of her conversation with Ms Sturgeon.

The memo was a second-hand account by a civil servant who was already warning about its plausibility. But for a Liberal Democrat MP whose party faced wipeout in the SNP surge, the chance to undermine a rival party’s leader may have appeared irresistible.

That in no sense justifies Mr Carmichael’s actions, which have left him facing calls for his resignation after he admitted sanctioning the leak. His position cannot be defended; bad enough was his initial public indifference to the memo’s publication. “This is the middle of an election campaign. These things happen,” he said last month.

That attitude was already the definition of an old-style politics voters are deeply sick of, and they arguably gave their verdict on that cynical view at the polls. (Notably, Ms Sturgeon’s reaction was “elections should be a battle of positive ideas and that’s how I’ll continue to campaign”.) Now it emerges that Mr Carmichael’s phrasing was disingenuously passive. This “thing” happened because he sanctioned it. He has admitted authorising the action in the face of a Cabinet Office investigation that identified his special advisor as the source of the leak. He could hardly deny it.

This story of deceit throws a different light on suggestions that somehow SNP MPs cannot be trusted to sit on the UK Intelligence and Security Committee in case they abuse confidential information. Can the trustworthiness of their fellow MPs stand up to the same scrutiny?

For Mr Carmichael is not merely guilty of political cynicism. His suggestion that he had not seen the memo but had been aware of its contents was already perilously close to deceit. His appearance on Channel 4 news, when he stated that he had only become aware of the issue when a journalist phoned him about it, is impossible to reconcile with yesterday’s report. It was a clear lie.

Mr Carmichael accepts that he would have to have resigned if he were still a government minister. In some ways he is fortunate he is no longer in that position. Can he remain as an MP? The margin by which he was re-elected was just 817 votes and, had his actions been exposed before May 7, it is questionable whether victory might have been achieved.

Had the LibDems and their Conservative partners delivered their 2010 pledge to allow constituents to force an election if their MP were guilty of wrongdoing, Mr Carmichael would almost certainly be facing such a recall.

He says he believed at the time that sharing the information in the memo was in the public interest. It is now in the public interest for him gravely to consider his position.