Before this thread runs amok (like it hasn't already) I think everyone here can agree that the taking of another life is generally not going to be God's first choice for anyone. However - there are varying degree's quantifying the "wrong" as it were. In a eutopia, there would never be a circumstance that would warrent "killing" anyone. It is only under degree's of extreme agression that justification is even considered. These are exceptions to the commandment. These would be self-defense, those who go off to war, or human error in a dangerous environment. (driving in a car, getting a flat tire and causing a fatal accident comes to mind)

As with any commandment - God isn't necessarily forbidding the choice to break the "law", just making man aware that for any wrong action there is going to be a consequence. Despite the level of justification - the degree of "pre-meditation" is going to be met with the degree of consequence. However, the consequence is not necessarily swift, nor immediate. But God is not mocked. He's fully aware of the intent, and expects man to face the reality of their own actions.

This - to me - is the intention of the commandment in the first place. I'm more than willing to adress or consider alternative interpretations here - but it seems petty to try and equate a soldier going to war with an unrepentant serial killer.