Pakistani-born Faisal Shahzad has been a US citizen for only one of his 30 years. Now he's under arrest for last Saturday's attempted car bombing of Times Square.

He was charged yesterday with terrorism and attempted use of a weapon of mass destruction. But the case raises the question: Is Shahzad a traitor, and should he be charged with treason?

The answer is partly a question of law -- and partly a question of prosecutorial judgment.

Treason, sometime referred to as "high treason," is an act of treachery or breach of faith against one's own country. Only individuals owing allegiance to the United States can be charged with treason against the United States.

Article III, Section 3, Clause 1 of the US Constitution states: "Treason against the United States shall consist only in levying War against them, or in adhering to their Enemies, giving them Aid and Comfort. No person shall be convicted of Treason unless on the Testimony of two Witnesses to the same overt Act, or on Confession in open Court."

The Constitution thus defines treason -- but leaves to Congress the task of making treason a crime. It did so in Title 18 of the United States Code, in section 2381. In part, the statute reads, "Whoever, owing allegiance to the United States, levies war against them or adheres to their enemies, giving them aid and comfort within the United States or elsewhere, is guilty of treason." The maximum possible punishment for anyone convicted of treason is death, with a mandatory minimum sentence of five years' imprisonment and a $10,000 fine.

Prosecutions for treason are rare in the United States, with fewer than four dozen such cases brought since our nation's founding. As noted in "The Heritage Guide to the Constitution," one reason is that constitutional standards associated with the definition and proof of treason are specific and quite high.

Hostile, subversive or volatile acts -- even when directed towards the whole polity -- may fall short of treason. For example, crimes such as homicide, providing material support for terrorism -- even using a weapon of mass destruction -- have been prosecuted under other criminal statutes.

Prosecutors often choose to charge terrorists with those substantive crimes -- which cover the same exact criminal conduct -- rather than treason, because it's easier to prove their case. In non-treason criminal trials, for example, there is no requirement that two witnesses testify against the defendant to secure a conviction. And penalties for those convicted of the non-treason crimes are often stiff -- including a possible life-in-prison or death sentence.

But charging someone with treason plainly conveys a stronger moral disapprobation than some of the more easily provable charges. The Shahzad case will certainly feed the already-bubbling debate about whether there should be more prosecutions for treason, especially in the current war against terrorists.

Indeed, this war has already brought the first indictment of a US citizen for treason since 1952, on Oct. 11, 2006 -- of Adam Gadahn, a k a Adam Pearlman.

Gadahn grew up in California, converted to Islam and moved to Pakistan, where he eventually became a senior commander to Osama bin Laden. As an al Qaeda media adviser, he has appeared in numerous terrorist propaganda videos spewing hatred of and violence toward the nation of his birth. He remains at large.

Whether prosecutors will charge Faisal Shahzad with treason remains to be seen. The decision should be driven by the evidence collected, the number of witnesses against him, the sound exercise of prosecutorial discretion and the array of other charges available to prosecutors.

Charles "Cully" D. Stimson is a senior legal fellow at The Heritage Foundation, former deputy assistant secretary of de fense for Detainee Affairs (2006-2007), and a former local, state, federal and mili tary prosecutor.