Tommy Robinson has been jailed for nine months after being found guilty of three counts of contempt of court.
Robinson was sentenced after a two-day hearing last week. He will serve up to half of the total sentence after the judges noted 138 days of time served.
In sentencing, the judges - Dame Victoria Sharp and Mr Justice Warby said: "The contempts we have found proved were not ones of deliberate defiance. In the event neither the trial nor the trial that followed were prejudiced. Nevertheless his conduct amounted to a serious contempt."
They continued: "We are in no doubt a custodial threshold is passed in this case. Nothing less than a custodial penalty would reflect the gravity of the conduct.
"The main purpose of the penalty in this case is deterrence."
The charges against Robinson - who was tried under his real name of Stephen Yaxley-Lennon - relate to live streams that he made outside Leeds Crown Court during the trial of several men from Huddersfield, who were accused of grooming children.
The broadcast, which lasted for around an hour, was seen by around 250,000 people after it was broadcast on Facebook.
The case against Yaxley-Lennon was based on reporting restrictions that were put in place surrounding the case. They prohibited any details of the case being published until the end of a series of trials that involved 29 defendants.
However, the live stream took place during the time period of jury deliberation in the second trial on 25 May 2018.
Andrew Caldecott QC, prosecuting, said that the defendant failed to check for restrictions and told the court of 'inconsistencies' in accounts given by Robinson with regards to whether he checked for restrictions or not.
He told the court: "Even if he did not know for certain the terms of the order, he knew the existence of such an order was likely and again was subjectively reckless."
Robinson said: "I took the view that it didn't matter if I wasn't going to report on the details of the case, and that if I was only going to stick to details in the public domain, it didn't matter."
The former English Defence League member claimed that he took action to ensure that he was not in contempt, and spoke only about publicly available knowledge.
The far right, anti-Islam activist was previously jailed under the Contempt of Court Act in May 2018, but was released on appeal before the UK Attorney General ruled that it was in the public interest to bring a second trial.
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