Law is what tries to make life fair. Law can deliver justice when it is not.
Where does the law come from?
Law is a man-made phenomenon and therefore there is always a choice whether to follow it or not. If you do not follow the law, you will not die, so nature has no bearing on the laws of man. The law is something the human race has created to regulate society by introducing fairness, justice and equality. It is set by courts and governments and applies to everyone within their jurisdiction. There is not an option to opt out. Disobey and there will be consequences.
Why do we need the law?
If someone attacks you and steals your money, the law protects you by requiring the police to firstly find the culprit and then the courts to punish that person. You are protected from the attack because the threat of legal action is a deterrent, but also society is protected from the individual in the future.
If someone sells you a watch which they say is gold and you later find that it is a cheap painted metal, the law says they must refund your money and be prosecuted for trying to trick you.
If you are black and are turned down for a job because you are not white, the law will punish the company that took that decision.
We need the law to ensure fairness in society.
What if we don't follow the law?
If nobody follows the law, the result is anarchy. This means fairness will be lost from society and only the richest or the meanest will prosper. The rewards of life only become available to those who can afford them or fight for them. Hard work will no longer result in success. Who likes pie?
