I was always told the age of reason was 8 years old, and from that age forward you should be aware of the consequences of your actions, but this is apparently not true since in their wisdom the legislative bodies of a number of jurisdictions (DC comes to mind) it doesn't matter what you do or how many time you do it as long as you're under the magic age limit the most you'll get is a severe talking to and "probation" where you're turned loose on the community to show how reformed you are.
When I was growing up the age of reason was about 12 but then again we did not have violent tv shows, video games or the internet. Now kids have lost their innocence by age 5 and curse like sailors when they go to Kindergarten.