Tommy Robinson is facing jail after being found in contempt of court by High Court judges for filming defendants in a criminal trial and broadcasting the footage on social media.
The political activist filmed defendants in a criminal trial at Leeds Crown Court in May 2018, livestreaming the video on Facebook.
Judges were told yesterday that his actions had been "reckless", and they today ruled that his conduct "amounted to a serious interference with the administration of justice".
Robinson denied any wrongdoing, saying he did not believe he was breaching reporting restrictions and only referred to information that was already in the public domain.
But Dame Victoria Sharp, sitting at the Old Bailey with Mr Justice Warby, found him in contempt in three respects.
She said the court will consider what penalty to impose for the contempt, and give full reasons for the decision, at a later date.
Contempt of court carries a maximum sentence of two years.
Supporters of Robinson began chanting "shame on you" outside the Old Bailey as the verdict filtered through.
Hundreds of his fans have been congregating outside of the court over the last two days.
They maintain he is innocent.
Robinson, wearing a blue jacket, blue shirt and jeans, showed little reaction as the judge announced the decision.