Checks and balances delay the advent of certain political wrongs, but eventually the ball can't be kicked down the road any further.
The Founder, James Madison, mocked rules written down with pen and ink, of the form "Executives may only execute the law, not make it," as "parchment barriers" because bad men would ignore them. He thought checks and balances more realistic because ambitious men in each branch would be kept from doing the things the other branches were supposed to do by equally ambitious men in those other branches, who were in competition with them.
The problem with this argument is that checks and balances are not self-enforcing; rules of the form "executives may exercise only certain checks, not others" are still parchment barriers.
I think Madison realized this, otherwise he would not have emphasized in his remarks at the Virginia ratifying convention that no republic can get along without virtue. Apparently, then, he mocked the former kind of rule not because the willingness to follow it required virtue, but because (at least in his judgment) the willingness to follow it to required less virtue than the willingness to follow the latter kind of rule. To put it another way, he did not judge the latter kind of rule to be self-enforcing. He only judged it to be more nearly self-enforcing than the former kind.
Unfortunately, he didn’t explain under what circumstances this judgment might be true. I say “unfortunately,” because the willingness to follow the former kind of rule is disappearing. The members of the branches exercise checks they shouldn’t; for example the president circumvents legislation he doesn’t like by that form of sheer decree called the executive order. They also fail to exercise checks they should; for example the legislature routinely allows the judicial branch to legislate from the bench, especially in matters it considers too hot to handle.
I certainly don’t disparage political activism on behalf of constitutional integrity. Trying to keep the operating system of the republic working properly is a good work. But in the long run, the effort is futile unless the culture itself can be renovated, because ultimately its proper operation depends on some residuum of virtue.
What makes renovation of the culture so difficult is that the law itself now does so much to habituate citizens to venality – which is a story for another day. But with God anything is possible.