Tweeters have joined forces to support Paul Chambers, the man convicted and fined for a Twitter message threatening to blow up an airport.
The Twitter community is angry that the 27-year-old accountant has failed to overturn his conviction.
A day after his appeal failed, two "hashtags" to highlight his situation remain top topics in the UK.
Free speech advocate Index on Censorship said the UK judiciary was out of step with social networks.
"The verdict demonstrates that the UK's legal system has little respect for free expression, and has no understanding of how people communicate in the 21st Century," said the organisation's news editor Padraig Reidy.
On Twitter, the furore over Paul Chambers' sentencing shows no sign of ebbing away.
Some 24 hours after his appeal failed, the "hashtag" #twitterjoketrial remains one of the top trending topics on the site.
A so-called "I'm Spartacus" campaign encouraging users to "re-tweet" his words has also become a huge hit.
The hashtag #IAmSpartacus is currently the number one trending topic on Twitter in the UK, with #twitterjoketrial in second place.
The I'm Spartacus campaign is inspired by the famous scene in the 1960s blockbuster, when slaves stood up one by one to claim "I'm Spartacus" in order to save their fellow gladiator from detection.
Paul Chambers was found guilty in May, convicted of sending a menacing electronic communication when he tweeted: "Crap! Robin Hood airport is closed. You've got a week to get your shit together, otherwise I'm blowing the airport sky high!"
Chambers is believed to be the first person convicted in the UK for posting an offensive tweet.
After the hearing, actor and Twitter fan Stephen Fry tweeted that he would pay Chambers' fine.
Comedian Dara O'Briain tweeted that the verdict was "ludicrous" while Peep Show actor David Mitchell said it was "punishment for flippancy".