He said they have the "best seats in the house'' and should ignore all outside influences.
"There are many news items, commentary, blogs and the like on the topics of these charges. They have a long and controversial history.''
He told them to "keep an open mind'' until after they had heard all the evidence.
Earlier in the day the four accused were asked to make a plea to the charges.
Iti and Kemara answered the charges in Te Reo Maori as they were read out by the court registrar.
In answer to the charge of belonging to a criminal group, Signer responded: "I'm innocent of all the charges.''
The indictment, filed by the Crown and read to the court this morning, alleges that the four were members of an organised criminal group between November 2006 and October 2007.
It is alleged that the group would have committed violent offences including murder, arson, intentional damage, endangering transport, wounding with intent, injuring with intent, aggravated wounding, discharging a firearm or doing a dangerous act with intent, using a firearm against police, committing a crime with a firearm and kidnapping.
The Crown have also listed the guns which the group are alleged to have had. They include a sawn-off shotgun, a Lee Enfield .303, a rifle, a sawn-off rifle and four other rifles.
It is also alleged that the group had Molotov cocktails and semi-automatic rifles, including an AK47 style rifle.
Outside court this morning, a group of about 100 supporters gathered, some flying Tuhoe and Tino Rangatiratanga flags.
Tuhoe kaumatua Tamati Kruger said supporters drove from Ruatoki and surrounding Tuhoe district to show solidarity with the accused.
"It is not a protest but rather they are here to rally, to attest to the concerns they have about justice here in New Zealand.''
He said the trial was a "dangerous blockade'' to progressing the relationship between Tuhoe and police.
"But also, it is a blockade for civil rights in the country.''
He said the relationship could not begin to heal until after the trial is finished.
"People may not have the emotional fortitude now, their tensions are high. We have to hope there is not too much damage done, otherwise it may be a one or two generational process.''
Also outside court were students from the Tuhoe Te Kura Kaupapa Maori a Rohe. The school is mostly made up of Tuhoe children living in Auckland.
Whaea Te Uru Piua Vaike said it was important for the 22 year 12 and 13 students to come to the court today.
"It is part of their education.''
She said the students were aware of what had happened in their homeland more than four years ago.
"Most of them know about that. They've seen it. They know how important for them it is to be here.''
Thirteen of the original defendants in the case had their charges dropped after the Supreme Court ruled that video footage taken by covert cameras was inadmissible.
But the court also found that alleged offending by the remaining four were serious enough to allow the Crown to use the evidence.
The Crown is due to open its case tomorrow. The trial is set down for three months.
