Scott Fenstermaker, the lawyer for accused terrorist Ali Abd al-Aziz Ali, said the men would not deny their role in the 2001 attacks but "would explain what happened and why they did it."
The U.S. Justice Department announced earlier this month that Ali and four other men accused of murdering nearly 3,000 people in the nation's deadliest terrorist attack will face a civilian federal trial just blocks from the World Trade Center site.
Mohammed, Ali and the others will explain "their assessment of American foreign policy," Fenstermaker said.
"Their assessment is negative," he said.
Fenstermaker met with Ali last week at the U.S. prison at Guantanamo Bay in Cuba. He has not spoken with the others but said the men have discussed the trial among themselves.
Critics of Attorney General Eric Holder's decision to try the men in a New York City civilian courthourse have warned that the trial would provide the defendants with a propaganda platform.
Dean Boyd, a spokesman for the Department of Justice, said today that while the men may attempt to use the trial to express their views, "we have full confidence in the ability of the courts and in particular the federal judge who may preside over the trial to ensure that the proceeding is conducted appropriately and with minimal disrupton, as federal courts have done in the past."