Truck loads of riot police were also deployed around the prison facility.
About 100 supporters of Aung San Suu Kyi gathered, as they have during earlier court sessions, sitting and standing as close as they could to the prison gates.
Khin Moe Moe, a lawyer and a member of the NLD party, was to appear as a defence witness during Friday's trial, held mostly behind closed doors since May 18.
The defence has not contested the basic facts of the case but argues the relevant law has been misapplied by the authorities.
They also assert that the American visitor, John Yettaw, was not invited and any intrusion was the responsibility of the security forces guarding the house.
Aung San Suu Kyi faces up to five years in prison if found guilty of the charges.
She has already been in detention for nearly 14 of the last 20 years, mostly confined to her Yangon residence.
Also being tried on the same charges as Aung San Suu Kyi are two women members of her party who have been her sole companions while under house arrest.
Yettaw, 53, of the US state of Missouri, is also on trial charged with trespassing.
He has pleaded not guilty and explained in court that had gone to warn Aung San Suu Kyi after he had a dream that she would be assassinated.
His family and friends have said he was working on a book and wished to interview her.
The trial has drawn international condemnation while opposition supporters have said it is a trumped up charge by the ruling generals to keep Aung San Suu Kyi out of elections to be held next year.
A UN mission to Myanmar last Sunday ended in disappointment after the country's military rulers refused to allow Ban Ki-moon, the secretary-general, to meet the jailed opposition leader.
Ban said Than Shwe, Myanmar's military chief, told him repeatedly that "he really wanted to agree to my request" but because she was on trial he did not want to be seen as interfering with the judicial process, or as being pressured by the outside world.
"I am deeply disappointed that they have missed a very important opportunity," ban was quoted as saying.