If marijuana is illegal, then smoking it, possessing it, cultivating it, selling it, etc., are all illegal, and will appear on your criminal record if you are caught. Criminal records, at least in my country, can be seen by employers. If you smoke weed - even just once - when you are 16, and get caught, then there is no doubt that it will come back to haunt you. When 50% of teenagers are doing it, it gets ridiculous.