The injunction, which Marr spoke about for the first time today in an article in the Daily Mail, where he allegedly admits being embarrassed by the order, was originally a super injunction which prevented the media from reporting an injunction was in place.
According to reports, this was challenged by Hislop and the super injunction was lifted, while an injunction remained on covering the story in the press, widely reported to relate to an affair by Marr with another journalist.
Last week Hislop claims he again challenged the injunction itself and this week Marr decided to speak publicly about the injunction and why he obtained it.
The Daily Mail reported the injunction was won in January 2008, to stop reports of the relationship. But now, the Mail reports, he no longer wants to prevent the story being published.
"I did not come into journalism to go around gagging journalists," he is quoted in the article.
"Am I embarrassed by it? Yes. Am I uneasy about it? Yes. But at the time there was a crisis in my marriage and I believed there was a young child involved.
"I also had my own family to think about, and I believed this story was nobody else's business. I still believe there was, under those circumstances, no legitimate public interest in it."
Speaking on BBC Radio 4 Today this morning Ian Hislop said he thought the original injunction was "outrageous".
"I thought this was a touch hypocritical since he'd written a piece specifically about privacy law in which he said judges should not determine privacy law, it should be determined by parliament.
"Therefore he had just done the exact opposite of what he believed.
"As a journalist he said 'I did not come into journalism to gag journalists', that's exactly what he did so I challenged it.
"I said to him and his lawyers this is outrageous. It cost a great deal of money but the super injunction was lifted.
"As the story changed he has now changed his mind, partly because I challenged the whole injunction last week.
"Now he's decided what he did got out of hand. The principle remains wrong, which he knows."
He added: "As a leading BBC interviewer, who's asking politicians about failures in judgement, failures in their private lives, inconsistencies, it was pretty rank of him to have an injunction while acting as an active journalist.
"I think he knows that, and I am very pleased that he has actually come forward and said 'I can no longer do this'."
Legal commentator Joshua Rozenberg, also speaking on the Today programme, said courts are were making up privacy law as they go along.
"But they are taking into account the rulings of the European Court of Human Rights and it's clear from their rulings that anything concerned with personal relationships attracts privacy protection.
"The courts are inevitability going to have find a balance between freedom of expression under article 10 of the human rights convention and the right respect for someone's private life under article 8, and even if parliament were to pass new legislation it's inevitable that judges would have to decide individual cases.
"... They're simply trying to find their way. All this row over super injunctions is missing the point.
"The real question is whether we should have a law of privacy that extends to protect people's private life and particularly their sexual affairs, and if we don't want that then it's necessary to change the law in this country and to modify the Strasbourg rules to say that somebody's affair is no longer part of their private life ...
"We are required to take into account the way the Strasbourg court is going.
"Whether you say that privacy extends to someone's extra marital affair or not is something on which I think our own courts could develop their own jurisprudence.
"In Andrew Marr's case it was a super injunction originally that was challenged and it then became possible to say he had obtained an injunction.
"Strictly speaking this injunction is still in force today, the fact that he has chosen to speak about it means we're in no trouble if we repeat what he says in a newspaper interview but we certainly can't say who the individual concerned is."
Image by Damo77 on Flickr, some rights reserved
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