The trial is the culmination of Operation Cleansweep, a 3-year effort by government officials. The defendants contend that they are being prosecuted for the free exercise of speech. Therefore, the prosecution will have to prove that the defendants urged "imminent action" rather than simply advocating the overthrow of the government, which courts have ruled is protected speech. The government charges that the conspiracy began in 1983, when Posse Comitatus member Gordon Kahl died in a shootout with law enforcement officers near Smithville, Ark. Kahl killed two Federal marshals in North Dakota the previous February and was subsequently sheltered by supporters. The government also contends that the defendants conspired to murder a judge and an FBI agent; held secret meetings that plotted direct violent action against the government; and planned to develop an Aryan army by robbing banks, counterfeiting, and murder.