Hundreds of protestors gathered outside Leeds Crown Court ahead of the trial of British National Party leader Nick Griffin on race hate charges.
Mr Griffin and BNP member Mark Collett, both deny charges of using words or behaviour intended or likely to stir up racial hatred.
They were charged in April last year after a BBC documentary on the party in West Yorkshire was screened in 2004.
The judge has warned demonstrators not to try and influence the proceedings.
A jury has been sworn in but the start of the trial was postponed to Tuesday.
Mr Griffin, from Welshpool, mid-Wales, is accused of four counts of the charge.
The charges relate to two separate incidents on 19 January and 5 May, 2004, which were recorded during the documentary, The Secret Agent.
Party activist Mr Collett, from Rothley, near Leicester, faces eight charges.
A BBC reporter at the scene said up to 600 opponents of the party demonstrated outside Leeds Crown Court as they waited for Mr Griffin and Mr Collett to arrive at court.
They were kept apart from up to 150 BNP supporters by a heavy police presence.
Five people were arrested for public order offences during the demonstrations.
The Recorder of Leeds, Judge Norman Jones, began proceedings by warning the demonstrators not to try and influence the proceedings.
He said documents they were handing out could be seen as “an attempt to undermine the British Justice System” and urged them to stop.
“Outside this court today two groups of people have seen fit to come to make massive demonstrations expounding the views of two sides of a particular argument, he said.
“People have every right to expound views in relation to any argument. This is a free society and it is important that public demonstration is permitted.
“It cannot be said too strongly that if some of those, in either group, are trying to act in a way in which they can influence this trial they will not succeed in doing so.”
Potential jurors were also warned not to take any documents from demonstrators and asked whether they felt able to approach the case in a fair and unbiased way.