"The defendants were members of a secret organization, a terrorism support cell, based right here in South Florida," Assistant U.S. Attorney Brian Frazier told jurors in his opening statement. "The defendants took concrete steps to support and promote this violence."
Attorney Jeanne Baker, representing co-defendant Adham Amin Hassoun, called the prosecution's case "a totally false picture."
While Hassoun, a 45-year-old Palestinian, had strong political opinions and was "a big talker," his sole aim in providing support for groups overseas was to assist oppressed, persecuted and needy Muslims, Baker said.
"He was helping to protect and defend Muslims from murder. That is not an intent to commit murder. That is just the opposite," she said.
Lawyers for Padilla and his other co-defendant are scheduled to deliver their opening statements later Monday.
Prosecutors and defense attorneys have spent months battling over issues ranging from torture allegations to the meaning of "jihad." They pored over classified material and Arabic translations and traveled overseas to interview witnesses and spent weeks picking a jury.
If convicted, the three defendants could face life in prison. The trial is expected to last into August.
Padilla, a 36-year-old former Chicago gang member and Muslim convert, has been in federal custody since his 2002 arrest at O'Hare International Airport. He was initially accused of plotting to detonate a radioactive "dirty bomb" in the United States and held for 3 1/2 years as an enemy combatant at a Navy brig, but those allegations are not part of the Miami indictment.
He was added to the Miami case in late 2005 amid a legal battle over the president's wartime powers of detention involving U.S. citizens. His lawyers had fought for years to get him before a federal judge.
In court Monday, Frazier told the court that Padilla agreed to be recruited by Hassoun as a prospective mujahedeen fighter to be trained by al Qaeda in Afghanistan.
Hassoun and the third defendant, Kifah Wael Jayyousi, 45, provided other Islamist fighter recruits, military equipment and money for conflicts in Lebanon, Chechnya, Somalia and other global hot spots, often using Islamic charitable organizations as a conduit, Frazier said.
The defendants sought separate trials, but their motions were denied by U.S. District Judge Marcia Cooke. She ruled the government had ample evidence that the three were connected in a conspiracy, with Hassoun and Jayyousi as jihadist recruiters, fundraisers and suppliers and Padilla as one of their recruits.
To prove a conspiracy, prosecutors will have to show that each of the three was involved in at least one act to provide material support to extremist groups.
In Padilla's case, a key piece of evidence is an application to attend an al Qaeda training camp in Afghanistan that prosecutors say he completed in July 2000. They also say it bears his fingerprints.
Defense lawyers will seek to raise questions in jurors' minds about the authenticity of the form, whether Padilla actually completed it himself and if there might be an alternative explanation for the presence of the fingerprints.
"The crimes he has been charged with pale in comparison to the initial allegations," said University of Miami law professor Stephen Vladeck. "This is a far cry from being a major front in the government's war on terrorism."
For Hassoun and Jayyousi, who were under FBI surveillance for much longer than Padilla, the keys may include the jurors' interpretations of hundreds of phone calls intercepted with wiretaps, the purpose of various money transfers, and the meaning of items in Jayyousi's newsletter.