This week, a military judge refused the defense's request to drop a charge of aiding the enemy against Pfc. Bradley Manning. If convicted on that charge, Manning could face a life sentence.

Manning, 25, has already pleaded guilty to 10 lesser charges for leaking 700,000 intelligence files, videos, and diplomatic cables to WikiLeaks in 2010. On those charges alone, he could face up to 20 years in jail.

The decision to charge Manning with aiding the enemy has been criticized by civil rights groups, with Amnesty International condemning it as "ludicrous." Others have defended the judge's decision.

"Manning had privileged access to restricted information," Steven Aftergood, director of the Project on Government Secrecy at the Federation of American Scientists, tells The Boston Globe. "Not only did those records expose individuals to potential retaliation, but their publication signaled that the U.S. could not guarantee confidentially to others."

If the judge, Col. Denise Lind, announces a guilty verdict, it could have wide implications for those who leak confidential information in the future.

What constitutes aiding the enemy?
Aiding the enemy is a very serious charge, one punishable by death. The prosecution in the Manning case isn't pursuing the death penalty, instead opting for life in prison without parole. Still, the fact that they could have gone that route underscores the gravity of the charge.

Yochai Benkler, co-director of the Berkman Center for Internet and Society at Harvard, explains the origins of the law in the New Republic:

In the past, it was used in hard-core cases where somebody handed over information about troop movements directly to someone the collaborator believed to be "the enemy," to American POWs collaborating with North Korean captors, or to a German American citizen who was part of a German sabotage team during WWII. But the language of the statute is broad. It prohibits not only actually aiding the enemy, giving intelligence, or protecting the enemy, but also the broader crime of communicating — directly or indirectly — with the enemy without authorization. [New Republic]

The crux of the prosecution's position is that Manning shared information with WikiLeaks knowing that al Qaeda or other terrorist groups could read it.

What does it mean for future whistle-blowers?
A guilty verdict could be disastrous for would-be whistle-blowers, writes Slate's Emily Bazelon:

It implicates all kinds of people who publish things that could hurt U.S. interests by tarnishing our image abroad. Journalists do this routinely; so do plenty of people on social media. It's called free speech. Most of the critics have no access to the kinds of damaging goods that Manning had. But now when they do, they will have to fear that publishing it is the legal equivalent of deliberately handing it to terrorists. [Slate]

Before the internet, one could reasonably expect that information handed over to the local paper wouldn't find its way across the ocean and into the hands of terrorists. Today, information shared online is available almost everywhere, meaning any leak could be construed as communicating with the enemy without authorization.

While the way we share information has changed, the law hasn't, resulting in a blurred line between whistle-blowing and far more serious crimes.

"There are very important differences between those who send information to the enemy with the intent of aiding the enemy and those people who release information to the public with the intent of informing the public debate," Mary-Rose Papandrea, a law professor at Boston College, tells NPR. "It's time for our legal system to draw some clear distinctions between these two categories."

The prosecution has said that it would have charged Manning with aiding the enemy even if he had leaked the documents directly to The New York Times instead of WikiLeaks, which could have relevance in any future case against Edward Snowden, who has applied for asylum in Russia after leaking information about the NSA's electronic surveillance program to The Guardian and The Washington Post.

"You don't need specialized intelligence training to know that terrorists use the internet," Elizabeth Goitein, co-director of the Liberty and National Security Program at the Brennan Center for Justice, tells the Los Angeles Times. "By this logic, any military officer who discloses information to the media or posts it on the internet could be charged with aiding the enemy. That's not consistent with the purpose of the law, and it could have a dramatic, chilling effect."