At what age should a child wear a seat belt?

I am not very familiar with the laws about a child wearing seat belt in other countries. But here in my country, I always let my girls wear seat belt at the back of the car. I've seen a lot of couples carrying their child on their lap and didn't bother to wear seat belt. This is a very dangerous practice and yet the government didn't deemed it important to implement a child safety practice on the road. How sad. :/

I have lived in Connecticut my whole life and honestly yes your son should have had a booster seat. In Connecticut your child is saposed to be in a booster up untill they are 6yrs old and 60 pounds. My middle daughter is 6 and almost 60pounds but I still make her sit in a booster seat for her safety.

This is what I found researching the net. For Virginia the law is Children between the ages of one and four and weighing between 20 and 40 pounds can be in a forward-facing, forward-facing only, or convertible child safety seat, or a high-back booster or harness, installed in the back seat of the vehicle. Children between the ages of four and eight can be in a high-back or no-back belt-positioning booster, installed in the back seat of the vehicle. If the child is under the age of eight but at least four feet and nine inches tall, a booster isn't required. A general rule of thumb is that children should be in a booster until their knees bend over the edge of the seat when sitting properly. You may want to use a seat belt adjust for some time thereafter. Kids should always use a seat belt The law is under 12 is in the back seat