Credit: Slug Signorino

As far as I can tell, nations have stopped formally declaring war since the end of World War II. But can war only be declared between nations? With the rise in terrorist groups, could the U.S. or another country declare war against Al-Qaeda or Isis or some other group rather than another nation? Or is any declaration of war just plain irrelevant these days? —Steve Mirro

How quaint, Steve. You’re talking about war like it’s a card game played by Boy Scouts, with rules enforced by creepy grown men wearing khaki shorts. Back here in reality, though, the U.S. isn’t going to forgo its milk and cookies because it launches a missile at someone it wasn’t supposed to. Because that’s how the international system works: laws are only as strong as the willingness of the most powerful country, or group of countries, to back them up.

That said, you’re right: While formal declarations of war were never exactly required, they definitely used to be more common. Between 1800 and 1950, political scientist Tanisha Fazal has pointed out, approximately half of all interstate “wars”—protracted and intense armed violence involving two or more states—were declared. Since then, however, we’ve had about the same number of conflicts, but only three of them have been declared, and none of those by a so-called Great Power, like the U.S., the UK, China, France, etc.

So what accounts for the decline? At this point, declaring war is worse than irrelevant—it’s basically all downside and no upside. Even for powerful countries, international organizations like the UN can make it a pain in the ass to break the rules. This is especially true lately: in 1898 there were three codified laws of war; by 1998 there were 33. Certain strategies and weapons aren’t allowed, and the military must be trained to exacting specifications. Lack of compliance means the possibility of being tried for war crimes. (Under U.S. military law, declaring war also empowers the military to court-martial its private contractors; whether you see this as a benefit or a hindrance may depend on how cynical you are about things like the Abu Ghraib affair.) And a declared war affects countries not directly involved: neutral states must remain impartial in trade, commerce, and diplomatic relations; alliance obligations can be invoked.

As a result, states now tend to avoid saying the W-word even when dispatching roving groups of armed personnel to foreign lands. Even though UN laws apply to “armed conflict,” which ought to override the declaration problem, the lack of labeling makes it harder to identify aggressive behavior and therefore trigger punitive action.

In this context, then, George Bush’s decision (OK, we all know it wasn’t his decision) to declare a legally confusing “War on Terror” was a well-calculated move. Congress, the only governmental branch technically empowered to declare war, never did so (though it did authorize military force). But the shocking visibility and scale of the 9/11 attack allowed the U.S. to justify belligerent military objectives that were both widespread and vague. In Bush’s words, the “war” wouldn’t end until “every terrorist group of global reach has been found, stopped, and defeated.”

The combined facts that (a) the United States in 2001 was the world’s undisputed leading power, (b) the attack scared our Western allies too, and (c) it marked a new era of warfare against organized yet transnational non-state actors meant that the U.S. government had more or less free rein to respond however it wished. International law hadn’t adapted to deal with new, post-Cold War circumstances (and arguably it still hasn’t). For instance, since the object of aggression wasn’t a state, the U.S. used the umbrella term “terror” to justify attacking any terrorist, in any country, without warning. CIA agents used a drone to kill six men in Yemen in 2002. But Yemen didn’t recognize this act as armed conflict on its land, nor did it or the U.S. consider themselves at war with one another.

Another political benefit (and humanitarian nightmare) of waging quasi-war was made manifest in the November 2001 executive order titled “Detention, Treatment, & Trial of Certain Non-Citizens in the War Against Terrorism”—also known as the catastrophe of Guantanamo Bay. The order authorized the Defense Department to detain potential enemies of the state, citing as justification the national emergency then in progress. What this meant in practice, administration lawyers would later explain, was that the detentions would continue until all the terrorists in the entire world were captured or eliminated—i.e., as long the U.S. government felt like it.

The grim possibility here is that efforts to impose humanitarian law on the practice of war have been at least in part counterproductive: Where once they might have played by at least some of the rules, states now have a greater incentive to avoid them entirely. One wants to believe in progress, but it’s hard not to suspect that war can be made only so civilized, and no more. —Cecil Adams