In the wake of the Boston Marathon bombing, several commentators have asked why we label some acts of mass violence "terrorism" while others are considered ordinary crime. Why do we treat those two so very differently, despite the latter being responsible for far more American deaths?

The Terror Label

Author and attorney Glenn Greenwald wonders why we are so quick to label Boston "terrorism":

Over the last two years, the US has witnessed at least three other episodes of mass, indiscriminate violence that killed more people than the Boston bombings did: the Tucson shooting by Jared Loughner in which 19 people (including Rep. Gabrielle Giffords) were shot, six of whom died; the Aurora movie theater shooting by James Holmes in which 70 people were shot, 12 of whom died; and the Sandy Hook elementary school shooting by Adam Lanza in which 26 people (20 of whom were children) were shot and killed.

It's a fair question. From both a legal and national security perspective, whether Boston turns out to be a terrorist attack ultimately depends on the motivations of the perpetrators. If the brothers Tsarnaev acted to gain attention for a political cause or to further "political or social objectives," they're terrorists. Otherwise, they're merely mass murderers.

Presumably, though, the reason we jumped so quickly to label the act "terrorism" has to do with both the location and the means. The shooting sprees in question were at random locations and clearly one-offs; that is, there was no reason to believe Loughner, Holmes, or Lanza were going to strike additional targets if given the opportunity. The Tsarnaevs, by contrast, chose an iconic target with a massive media presence.

Yes, as Greenwald and others have suggested, we tend to consider bombs more terror-inducing than guns. Then again, Major Nidal Malik Hasan, the Fort Hood shooter, used a gun, as did John Allen Muhammad and Lee Boyd Malvo, the Beltway snipers. We considered them terrorists. Why? Because there was political motivation and because, in the latter case, the episodic nature of the attack seemed designed to induce terror, not merely to kill.

Hasan, Muhammad and Malvo had another thing in common with the Tsarnaevs: they were Muslim. Greenwald suspects that's why we're so quick to label them terrorists. But, while it would be foolish to dismiss post-9/11 anti-Islamic bias as a contributing factor, the fact of the matter is that we were calling the Beltway snipers "terrorists" long before their identities or religious beliefs were known. And Timothy McVeigh, the Oklahoma City bomber, was deemed a terrorist years earlier.

Gun Violence vs. Terrorism

Guardian columnist Gary Younge was among many to contrast the immediate calls for action after the bombing Monday afternoon with the Senate's failure "to pass even the most anaemic gun control measures in response to the Newtown shootings" on Wednesday. But there were all sorts of calls to impose restrictions on guns, do something about violent video games, and even overhaul our mental-health system in the wake of Newtown—just as there are every time there's a highly publicized incident.

Century Foundation fellow Michael Cohen makes a more salient point, in wondering why authorities shut Boston down, ordering citizens to "shelter-in-place" while a search for a 19-year-old fugitive took place, while "more than 30,000 Americans die in gun violence every year (compared to the 17 who died last year in terrorist attacks)." He concludes, reasonably enough, that we're treating the two threats disproportionately.

But it's not really that difficult to fathom why. The Boston Marathon bombing was a rare, specific event, and it was perfectly reasonable to fear that those behind it would kill others if not apprehended. Because authorities were able to accomplish that so quickly, the nation's attention was rapt. In contrast, most of us have long since dismissed the background threat of a follow-on al Qaeda threat as something that we live with without much thought.

Cohen also notes that there have been occasions of spree violence—he cites the 2002 DC sniper murders and this year's spree by disgruntled cop Christopher Dorner in Los Angeles—that were handled without a lockdown. But while the Boston shelter-in-place order was an overreaction, the situations were different in ways other than our fear of "terrorism." Indeed, the DC snipers were terrorists and, it turned out, Muslim. We didn't lock down the area because the DC metropolitan area and the shootings themselves were dispersed over a wide geographic footprint. Boston is tiny by comparison. Furthermore, as much as we international-security types scoff as the absurdity of federal law calling ordinary explosive devices "weapons of mass destruction," there's not much doubt that a bomb can potentially kill far more people than a bullet—or even a single gun.

The Lone Wolf vs. Organized Terrorism

Salon columnist David Sirota joins Greenwald in arguing that "white male privilege" explains why spree shooters like Loughner, Holmes, or Lanza are considered "lone wolf" threats while "non-white or developing-world terrorism suspects are often reflexively portrayed as representative of larger conspiracies, ideologies and religions that must be dealt with as systemic threats — the kind potentially requiring everything from law enforcement action to military operations to civil liberties legislation to foreign policy shifts."

But that's surely not the most reasonable explanation.

Hasan is being treated as an ordinary criminal, despite not being white and proudly proclaiming not only jihadist motivations for his shooting spree but claiming membership in al Qaeda. Why? Because he’s perceived as a lone wolf and his connections to al Qaeda are at best ephemeral.

The elder Tsarnaev brother was killed in a standoff with police (or, if not, when his brother drove over him escaping) but the younger was captured and being treated as an ordinary criminal—even though we knew they were Muslim by that point. Ditto the 1993 World Trade Center bombers. And Muhammad and Malvo. And Hassan. And Richard Reid (“the shoe bomber”). And Umar Farouk Abdulmatallab (the “underwear bomber”). And many, many more non-white perpetrators of terrorism and mass murder who were reachable by traditional law enforcement.

Similarly, while Oklahoma City was clearly a terrorist attack under any of the many working definitions, McVeigh and company were a tiny group acting alone. That they were tied to a fringe white supremacist "militia" was largely irrelevant, in that said militia wasn't behind the attack nor were they planning follow-on attacks. Further, McVeigh and company were easy to apprehend and try in our legal system.

The 9/11 plot was different. It was organized and perpetrated by a well-financed, well-organized group that had committed numerous previous attacks on United States targets—including a U.S. Navy vessel, two U.S. embassies, and a previous attempt on the World Trade Center—and had issued a manifesto declaring a war on the United States as part of a larger plan to take control of the Arab world. While many wanted—and still want—to treat this as a law enforcement matter, the scale, severity, and organization led to it being treated primarily as an act of war.

The Boston bombers, so far as we now know, were acting alone. One is dead and the other is in custody. So, they're likewise able to be tried within our legal system. What makes al Qaeda different is that they're active, organized and outside the reach of our institutions. While parts of it are attackable through the legal system and other parts through the financial system, there's almost certainly got to be an intelligence and military approach applied to the armed wing because they reside in places where extradition and the like are unworkable.

Acts of terror get more attention than everyday gun violence because they represent a broad, repetitive, and often organized attempt to kill while spreading fear throughout society. Gun violence—tragic as it may be—simply doesn’t reach that level.

James Joyner is managing editor of the Atlantic Council.