We are all familiar with how the death penalty works. A crime (usually murder) is committed. It's investigated by law enforcement. A suspect is arrested, charged with the crime, and goes to trial. The government shows the judge or jury the evidence against the accused. The accused can defend against the accusations. The jury delivers a verdict. If it's a guilty verdict, the defendant might be sentenced to death.

The process, from arrest to sentencing, is the Fifth Amendment in action, the part that states: "no person…shall be deprived of life, liberty or property without due process of law."

But earlier this year, the Obama administration asserted it has the authority to carry out "targeted killings" of U.S. citizens outside armed conflict zones. In February, then-Director of National Intelligence Dennis Blair told the House Intelligence Committee that the U.S. was authorized to take “direct action” against suspected terrorists and that “if we think that direct action will involve killing an American, we get specific permission to do that.”

It was reported widely, in fact, that the government keeps secret "kill lists," which function as standing authorizations to use lethal force against anyone on the list, including American citizens.

Today, the ACLU and Center for Constitutional Rights (CCR) filed a lawsuit challenging the government's asserted authority to carry out targeted killings of U.S. citizens outside armed conflict zones.

Now, no one disputes that the United States is at war. But wars are waged in specific geographic areas. Currently, the U.S. is at war in Afghanistan and Iraq.

The U.S. is not at war in Somalia. Yet that is where a missile strike killed Ruben Shumpert, a U.S. citizen from Seattle.

The U.S. is also not at war in Yemen. Yet that is where Anwar al-Aulaqi, a U.S. citizen, is purportedly in hiding, and where the government has attempted to assassinate him as many as a dozen times using armed drones.

The Constitution protects all Americans' right to life, whether they're living at home or abroad. If the government thinks you should be dead, it should at least tell you why. The fact that the standard that puts Americans on the "kill list" is a secret is itself unconstitutional. As our complaint states, "U.S. citizens have a right to know what conduct may subject them to execution at the hands of their own government. Due process requires, at a minimum, that citizens be put on notice of what may cause them to be put to death by the state."

No one would dispute either that the United States has the right to protect and defend itself against its enemies. But outside of zones of armed conflict, both the Constitution and international law prohibit targeted killing except as a last resort to protect against concrete, specific, and imminent threats of death or serious physical injury. The fact that many on the "kill list" have been on the list for months makes clear that the administration’s targeted killing program is broader than the law permits.

The government isn't perfect, and this targeted killing program leaves too much room for error. The American government detained almost 800 men at Guantánamo as terrorists, only to release 600 of them after it was found that there was insufficient evidence to hold them. In other words, it made mistakes. Lots of them. And the consequences are far more serious when the end result is death.

A few weeks ago, ACLU deputy legal director Jameel Jaffer was on Democracy Now talking about the targeted killing program. He said: "A lot of us agree that the last administration's argument for worldwide detention authority, the authority to detain people without charge or trial, was extreme and unlawful. This administration is claiming worldwide execution authority." It's death without due process, far from any battlefield, which is alarming, dangerous, and unconstitutional.