Big Banks can never be trusted to follow the rules. Evidence of big banks breaking the rules stems from incidences as far back as the 1920's. Banks will continue to break the laws and rules because they seldom get caught. They would rather break the rules now and get caught later. Big banks have lied about loans, approval rates, interest rates, and some banks get caught overcharging customers on a daily basis. Scandal has surrounded big banks and will continue to until government comes in and regulates how much power big banks should have.
I personally believe that big banks will at least attempt to use their financial strength to bend and break the rules. Believing that they will be able to "buy" their way out of any situation they may get themselves into or leverage the fact that their large customer base will be negatively effected therefore negatively effecting the economy if they are punished for not following the rules.
No, big banks cannot be trusted to follow the rules. Big banks are in it to make money, and will bend rules to do it. You can tell by the number of banks that bought up mortgages, just to be bailed out by the government once the housing crisis hit an all time low.
No, I really don't think that big banks can be trusted to follow the rules. It's all about loop holes and what is going to make them the most profit. Almost any corporation with enough power to get a government bail out, can not really be fully trusted with any thing