Barber was among the dozen on trial on charges of disrupting business at the General Assembly in April.
Barber did not take the stand, and his lawyer will not say if he plans to put him or his co-defendants on the stand.
Tuesday was one of the longest Moral Monday trials, and there are hundreds more to go, which is part of what has critics fired up.
Barber and 11 others listened as lawyers argued the two sides and grilled legislative policy.
According to the lead lawyer for the defense, Irv Joyner, the rules that govern who can protest at the General Assembly, and how, are going to be critical in how the trial plays out.
"Among the things they prohibit, or seek to prohibit, is the displaying of political messages in the General Assembly. The General Assembly is a body where political messaging is the focus of everything that goes on there," said Joyner.
The legislative rules were drafted back in 1987. Joyner says they are loose at best, and could be unconstitutional.
"It is unconstitutional, as a rule, to prohibit people from going to the General Assembly to voice their concerns," he said.
However, another lynchpin argument could be whether Barber and others went to the General Assembly specifically to be arrested.
"When you decide to engage in civil disobedience, one of the things that you ought to do is decide to accept the penalties that go along with that," said Mitch Kokai, Director of Communications at John Locke Foundation.
Yet, Joyner says there is a difference between going to be arrested and going knowing you could be arrested.
"There are some fundamental constitutional issues at work, here," he said.
The trial will continue Wednesday.
More than 900 people face charges of trespassing, failing to disperse, and violating building rules. Wake County District Attorney Colon Willoughby has given protestors a choice of paying a fine and performing community service or facing trial. Many protestors have chosen the latter - with varying outcomes.
In early October, Saladin Muhammad, who was the first protester put on trial, was ordered to pay a $100 fine. But a judge dismissed charges against husband and wife Vicki and Douglas Ryder.
Muhammad has appealed.
Legal experts say there is not much legal precedent for trespassing at the General Assembly, meaning there's not a lot of case law for judges to rely on.
Willoughby has expressed concern about the cost of putting so many protesters on trial and said it will tie up the courts.
The Moral Monday group is challenging decisions made by Governor Pat McCrory and the Republican-led General Assembly. They accuse conservatives of hurting North Carolina workers in various ways - including working to restrict voting rights and cuts to social programs.
Republicans counter they are working to promote growth in a fiscally responsible way.