The Attorney General Dominic Grieve has warned internet users that the law will crack down on abusers posting on social networking sites such as Facebook and Twitter, in the same way as it would should such activity take place in the street.
The warning came after a series of high-profile cases involving postings made on micro-blogging sites. In one case a student who mocked football star Fabrice Muamba after he collapsed and nearly died in a game was jailed for 56 days for a racially aggravated public-order offence.
In another, a blogger who threatened to force excrement through the letterbox of a local councillor was handed 80-hours' community service.
Mr Grieve likened posting on Twitter to walking into the pub and handing out flyers with offensive messages on.
"If somebody goes down to the pub with printed sheets of paper and hands it out, that's no different than if somebody goes and does a tweet. The idea that you have immunity because you're an anonymous tweeter is a big mistake," he said on BBC Radio 1's Newsbeat programme.
"I don't want to take action but if I think it is necessary to prevent crime, such as racially aggravated harassment, then I won't hesitate to do it," he added.
Mr Grieve has been grappling with the legal issues thrown up by wider internet use for some time. Last year he warned that use of the internet could jeopardise trial by jury, after acknowledging that juror's impartiality could be tainted if they were to research a case online whilst doing jury duty. Jurors are now warned by judges about the use of the internet during trials.
The issues raised by the internet were brought into sharp focus after the anonymity of Ryan Giggs was blown by 75,000 Twitter users who revealed that he was the footballer who had had an affair with former Big Brother contestant Imogen Thomas.
Mr Giggs was in possession of a 'super-injunction' at the time, forbidding reporting of his case or mention of his name. His lawyers failed in a bid to force Twitter to reveal the names of those who had breached the injunction after Mr Giggs' name was stated openly in the House of Commons by an MP objecting to the use of super-injunctions in such cases.
Mr Grieve reaffirmed that Twitter users are not beyond the law, and are not exempt from the enforcement of privacy orders.
"I will take action if I think that my intervention is necessary to maintain the rule of law," he said.
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