If you are 18 in America, you are (in priciple) apt to go to war, BUT, you can not legally buy a can of beer, BUT, don´t worry, you can legally buy an assault rifle! If ( God forbids) you break the law, and you are 18 or less, Courts can judge you as an adultt, BUT you still need to be 21, or more, to buy alcohol legally, BUT, you are legally permitted to buy a fire arm! Of course, everybody knows that.