That's in part because it appears no one charged with such a crime has ever taken their case to a jury -- until now.
In U.S. District Court in Phoenix on Tuesday, accused ISIS supporter Abdul Malik Abdul Kareem is doing just that. A Justice Department official said his case is thought to be the first of its kind to proceed to trial.
Kareem is charged with providing material support to ISIS in connection with a thwarted terrorist plot in Texas last year
His alleged co-conspirators were killed in a gun battle with police outside their intended target: An event featuring cartoons of the Prophet Muhammad deemed offensive to Muslims.
The attackers, Elton Simpson and Nadir Soofi, were wearing body armor and firing assault rifles when they were killed.
Simpson had been in contact with known jihadists prior to the attack, according to law enforcement sources.
Federal prosecutors say Kareem, Simpson and Soofi watched extremist videos together prior to the May 3, 2015, attack, including some depicting torture and executions.
The men allegedly conspired to commit jihadist attacks and considered multiple potential targets, including military bases, shopping malls and the site of the 2015 Super Bowl, according to a December 2015 indictment.
In preparation for the attack in Garland, Texas, prosecutors allege, Kareem arranged shooting trips in the remote desert outside Phoenix where he trained Simpson and Soofi how to shoot assault rifles. He then encouraged the men to carry out the attack, prosecutors allege.
In a pre-trial court filing, Kareem's defense attorneys wrote that their client "had no knowledge" of plans for the attack.
"Although he may have gone shooting with them in the desert and may have purchased ammunition for guns from a common source, he had no knowledge they were going to participate in such an attack," the court papers state.
Opening statements in the case are expected to begin Wednesday, said Cosme Lopez, a spokesman for the U.S. Attorney's office in Phoenix. The trial is expected to last five weeks.