British prosecutors back off harsh punishments for offensive messages on Facebook and Twitter

British prosecutors announced new guidelines on Wednesday making it less likely that Twitter and Facebook users will face criminal charges for offensive messages they post online.

The guidelines, intended to draw a line between genuine threats and misjudged jokes, have been published following a sharp rise in the number of prosecutions over the past two years, and resulting concerns over freedom of speech.

In one high-profile case, a man was convicted in 2010 for joking on Twitter about blowing up Robin Hood airport in central England after his flight was cancelled due to a snow storm. The conviction was quashed in July.

Under the new rules, Internet trolls who persecute individuals, make credible threats of violence or breach court orders -- for example on victim anonymity -- will still face charges, Director of Public Prosecutions Keir Starmer said.

But he said prosecutors should question whether to take action against those who post online messages that may be considered "grossly offensive, indecent, obscene or false", which are currently crimes.

If the message is swiftly removed, blocked, intended only for a small audience or not obviously something that would be tolerated in a normal social situation, or if the person responsible apologises, prosecution is not recommended.

"These interim guidelines are intended to strike the right balance between freedom of expression and the need to uphold the criminal law," Starmer said.

He said they "protect the individual from threats or targeted harassment while protecting the expression of unpopular or unfashionable opinion about serious or trivial matters, or banter or humour, even if distasteful to some and painful to those subjected to it".

The guidelines also take into account the age of the person responsible, noting "children may not appreciate the potential harm and seriousness of their communications, and a prosecution is rarely likely to be in the public interest".