And to further tear your argument, Spanish who have a "reputation" in Europe of crossing by red light and of having a bit more of loose attitude towards rules have a similar murder rate. 0.9 for Spain, 0.86 for Germany.

I think the factors are external rather than internal. I don't know exactly what causes it though. The higher availability of guns in the US? The fact that the prison system in the US does not reform but punishes instead and convert first time convicts into hardened criminals? Other factors?

I don't know but having lived in all three countries, I don't see that many differences in term of people's character that could explain the difference in murder rate.

Probably not the guns. Germany has about a third the rate of gun ownership the US does and its rates of serious violent crimes, both with and without guns are much less than a third those of the US. All of Scandinavia, Switzerland and Iceland have high rates of gun ownership and even lower crime rates.

The prisons might have an impact, but I think at least as important is the post-release re-integration in to society. The parole system in the US is set up more to ensure that released prisoners can be easily subjected to further punishment if need be than to help them lead productive lives.

An important factor is that those countries have a distinct culture and sense of community. People are more willing to hurt others they don't see as part of a group to which they are loyal. I actually see the lack of cultural homogeneity as a strength for the US overall, but I think it tends to lead to more crime.

Another important factor is the relative lack of poverty in northwestern Europe. Someone who sees none of their prospective ways to earn a living legally leading to a comfortable lifestyle is more likely to consider illegal and antisocial approaches.

In term of cultural homogeneity, I don't actually think there's much less cultural homogeneity in Europe compared to US. We do have a lot of immigrants from different cultures actually...

I do agree in term of poverty factor, for a country that is seen externally as being rather powerful and rich, there's a lot of inequality in the US with a very sizable underclass and a seemingly low upward mobility. This is the one thing I rather appreciate in Europe, education is almost free and opens a lot of opportunities that I probably wouldn't have had if I were american (even my tuition when I was an exchange student in the US was free thanks to that).

No offense, but could this be selection bias? You have certainly only talked to a selected subset of people..

I think if 80% of the U.S. population would want a thorough reform of their justice system, it would happen.

What exactly would an 'external' factor be for you?

What I mean by external factor is the laws, the way the criminal system is setup, the lack or not of reinsertion opportunities for ex-cons and so on. You might say that in a democracy all of this is decided by the people, but there's a certain inertia that sets in that mean that people have very little influence in changing things and there are powerful forces that try to keep things as they are (for profit or different reasons).