On paper, we have separation of powers.
Given human nature, each branch faces the temptation to use the legitimate power it has to gain illegitimate power at the expense of the other two branches. We have this perennial tug of war where one branch attempts to augment its power by taking power away from another branch, or vice versa.
Within limits, the system can survive. But ultimately, separation of powers is a honor system. It depends on each branch exercising self-restraint. aIf one or more branches refuse to play by the rules, then the system breaks down. It becomes unworkable.
When that happens, moreover, there may be no solution within the system. You can only have checks and balances on abuse of power if the abusive branch honors the checks and balances. Recall Andrew Jackson’s refusal to honor a Supreme Court ruling — now imagine a more thoroughgoing version of that rejection of the separation of powers.