Innula,
You are confused because you believe America is a system of laws, which, for the most part it is. But is also close to the old German system which is a system of customs and expectations, where unwritten norms have an iron grip on those who both follow and don't follow the norms to their own ill benefit. In many cases there is individual discretion. Attorney Generals and governors can selectively choose what laws to enforce, prosecutors can be selective about what charges to bring, contracts may be made on a handshake (less likely now, but still...) and even higher offices, even the presidency, has a lot of informal rules which can be selectively applied. In fact, Nightline back in the 80's did a "nuclear wargame" with retired Americans and Russians playing their former real-life roles, and while the Russians figured out the line of succession in less than a minute, the Americans were quibbling over it for a quarter of an hour.
It's all in the interests of efficiency and to some effect, calming the waters. It's results: generally a stronger economy and, with our history of extermination, slavery, and bringing in a lot of foreigners violently opposed to one another, peace.
It usually works, except when it doesn't, like in 1936. Consider yourself warned.