You probably felt pretty grown-up at 16 or 17. Perhaps you even thought you knew everything.

Given what you know now, maybe you realize how short-sighted you were. Back then, your narrow view of the world focused on yourself, and some of the things you did lacked reason.

It's in this lack of understanding that the Supreme Court found it unconstitutional to sentence Christopher Simmons to death on Tuesday. Seventeen at the time, Simmons murdered his neighbor in 1993 by tying her hands with electrical cable, leather straps and duct tape and pushing her off a railroad trestle into a river.

Brought before the Supreme Court, the split ruling changed the precedent for punishing 16 and 17-year-olds with the death penalty. The reasoning: It was unconstitutionally cruel under the Eighth Amendment, which bars the use of cruel and unusual punishments.

In his writing for the court, Justice Anthony Kennedy said of the defendant that "the State cannot extinguish his life and his potential to attain a mature understanding of his own humanity."

Although heinous crimes such as Simmons' should be met with meaningful punishments, when committed by those who might be too young to comprehend the ramifications of their actions, death is too far.

Many would argue death is a fitting punishment for such crimes, regardless of adult status, but the ages where citizens are given increased rights are not simply selected from cultural traditions; they are backed by scientific research that shows teenagers are impulsive, don't use sound judgment and have less ability to exercise self-control.

Children are growing up in a day and age where they are fed a stream of violent, fast-paced programming. This isn't to blame video games or movies for horrible crimes, but to take note of the fact that what kids are being exposed to might affect their psyche. With so many powerful messages, even more care must be used when examining factors that could shape the mind of a young killer. Chances are, it all won't be based in reality.

Within the world community, the United States has finally come in line with the overwhelming consensus that executing juveniles is wrong. According to the Guardian Unlimited Newspapers Web site, this belief had been ratified by every country in the U.N. Convention except the United States and Somalia, which has no recognized government.

When the death penalty is instituted, it is typically because a jury believes the accused will not feel remorse for their crime while imprisoned. In many cases, a teenager is unable to understand the depth of what they are doing, let alone the depths of remorse. Whether they will feel it or not won't be evident until they've matured enough to understand their actions.

A life in prison is not an easy punishment either. It is said there is no harsher judge than yourself. If there is anything decent within a person, or if they can eventually grow to understand decency, they'll have the rest of their lives to torture themselves with guilt.