These are a development of a type of court order requiring the injuncted information to be kept secret – colloquially, the “gagging order”.
The so-called “super-injunction” adds the gloss that details about the existence of the injunction itself cannot be revealed either. The idea behind this is to deal with cases where merely reporting that an injunction had been obtained to stop people talking about something that Mr X had done would result in the damage that Mr X was arguing he had a legitimate interest in preventing being caused.
The so-called “hyper-injunction” adds the further specific gloss that the injuncted information cannot even be revealed to an MP.
Cue lots of hyperbole about secret courts and the Magna Carta.
But is the idea of a hyper-injunction really all that objectionable in an appropriate case? It seems to me that if there is a legitimate reason for a temporary gagging injunction to be imposed, it is undesirable if the person principally subject to the gag can just lobby an MP to stand up and mention it in Parliament, thereby getting around the injunction with impunity (due to the doctrine of Parliamentary privilege, which means that anything can be discussed in Parliament and the fact that proceedings in Parliament can be freely reported*). This is presumably what the court had in mind in imposing the additional specific restriction on talking to MPs.
Rather, the real concern would be gagging orders – whether super or hyper or whatever – being imposed for too long a time period or being imposed in inappropriate cases or for inappropriate reasons.
*Edit 23/05/11: The law on this is not as clear as I had thought when I first drafted this. While reporting proceedings in Parliament would be a defence to a defamation claim, Lord Neuberger’s report on super injunctions states that it is not clear that reporting such proceedings is a defence to an action for contempt of court – (see paragraph 6.33). Nevertheless, when John Hemming MP today named in Parliament the footballer who is said to have obtained an injunction relating to his affair with Imogen Thomas, which restrained him from being named, a number of English newspapers appear to have taken Mr Hemming MP’s remarks as their cue immediately to publish his name and photograph on their websites.