Justice has been conceived of by the earliest of mankind and is one of the four cardinal virtues. It accompanies courage, temperance and prudence.
Justice must be in aid of the creation of equal and unbiased society. Where wrong acts are corrected in accordance to what the collected thoughts of one's community believe is fair. I would go further in saying. That in Justice is found against anti social behaviour and material theft. For maintenance of morally and socially acceptable rights.
If the government has already deemed an adult responsible enough to control their own finances, responsible enough to vote, and responsible enough to fight for their country, then certainly they should be deemed responsible enough to provide their own safety