People who post one-off offensive messages on social media could escape charges, the most senior prosecutor in England and Wales has suggested.
"The time has come for an informed debate about the boundaries of free speech in an age of social media," Keir Starmer, the Director of Public Prosecutions, said on Thursday.
One-off messages which do not form part of a campaign of harassment and are not intended to incite others are unlikely to lead to charges, Starmer signalled.
His comments follow a decision not to charge a man over comments made about Plymouth diver Tom Daley, and comes after a spate of several high profile cases of online 'trolls' going to court.
Student Liam Stacey was jailed for posting racist remarks on Twitter about Fabrice Muamba, as the footballer lay on the pitch after suffering a cardiac arrest.
Last week a man who posted a message on Facebook following the deaths of six British troops which said "all soldiers should die and go to hell" was found guilty of sending a message that was grossly offensive.
Earlier on Thursday Starmer announced no charges would be brought against a Welsh Premier League footballer who posted a homophobic message about Daley.
Daley, 18, and diving partner Pete Waterfield missed out on a medal at this summer's Olympics when they finished fourth in the 10m synchronised dive.
Port Talbot Town FC midfielder Daniel Thomas posted a homophobic message on Twitter, which was later distributed more widely, leading to his arrest.
But Mr Starmer said the message was "not so grossly offensive that criminal charges need to be brought".
Tom Daley's Twitter troll will not be prosecuted - with Starmer saying Daniel Thomas' Tweet was a "one off" offensive message
"This was, in essence, a one-off offensive Twitter message, intended for family and friends, which made its way into the public domain," he said.
"It was not intended to reach Mr Daley or Mr Waterfield, it was not part of a campaign, it was not intended to incite others and Mr Thomas removed it reasonably swiftly and has expressed remorse."
New guidelines for prosecutors are needed because this was one of a growing number of cases and there are likely to be many more, he said.
Estimates show there are 340 million messages a day sent on Twitter alone and "banter, jokes and offensive comment are commonplace and often spontaneous", Mr Starmer said.
"Social media is a new and emerging phenomenon raising difficult issues of principle, which have to be confronted not only by prosecutors but also by others including the police, the courts and service providers," he said.
"The fact that offensive remarks may not warrant a full criminal prosecution does not necessarily mean that no action should be taken."
Mr Starmer will hold a series of round-table meetings with campaigners, media lawyers, academics, social media experts and law enforcement bodies next month before the interim guidelines are published.