How Pressure Cookers Get Classified as a WMD

Accusing Dzhokhar Tsarnaev of carrying out a WMD strike at the Boston Marathon could offer prosecutors a clear route to a conviction, even though the two pressure-cooker devices used in last week's attack do not fit the accepted definition of a "weapon of mass destruction," academics and former federal prosecutors said on Tuesday.

Tsarnaev, 19, could face execution if he is convicted of "using and conspiring to use a weapon of mass destruction" in the twin explosions that killed three people and wounded more than 200 on April 15. The charge is possible due to an expansive legal definition folding such arms into a wider class of "destructive devices" that can include small explosives, even when such devices lack any of the chemical, biological, radiological or nuclear components associated with most WMD discussions outside of U.S. law.

"In some ways this is the easiest count to allege at this moment in time," said Michael Sullivan, a former U.S. attorney for Massachusetts. "The devices themselves fit very nicely within the statute."

"Within the next 30 days, the government will indict the defendant, and there I think you'll see some additional counts beyond the two counts in [Monday's] complaint, particularly if they develop evidence related to his terrorist activities," Sullivan said by telephone from Boston. Tsarnaev faces a separate charge of "malicious destruction of property by means of an explosive device resulting in death." His brother and suspected accomplice Tamerlan was killed in a Friday shootout with police.

The broad legal definition for "weapons of mass destruction" began to take shape in 1994, under one provision of a federal law better known for imposing a decade-long ban on manufacturing certain assault weapons.

The Violent Crime Control and Law Enforcement Act "beefed up the federal death penalty statutes and ... created these new offenses," said Richard Roper, a former U.S. attorney for the Northern District of Texas. "This is one of them."

Roper said the Patriot Act and a later 2004 law tweaked that statutory WMD definition, which federal prosecutors have used on numerous occasions since the Sept. 11 attacks in cases involving "conventional" explosives.

Weapons of mass destruction charges might be "a favored tool of prosecutors" because pursuing them does not involve clearing certain hurdles involved in other legal strategies, a Duke University public policy specialist suggested.

"You don’t have to get into the definition of whether this is terrorism or not, you don’t have to prove motivation, you just have to prove that the person has used [a destructive device] against any person or property in the United States," said David Schanzer, who heads the Triangle Center on Terrorism and Homeland Security.

"There’s an incongruity between the statute and the way the word ‘WMD’ is used [elsewhere], but I don’t see that as a problem," he added.

Roper said prosecutors sometimes pile a WMD accusation onto other charges to gain additional leverage in plea negotiations. Defense lawyers know such charges carry "the possibility of the death penalty, and sometimes that engenders more cooperation," he said.