Original: Through a system of separation of powers and the system of "checks and balances," each of these branches has some authority to act on its own, some authority to regulate the other two branches, and has some of its own authority, in turn, regulated by the other branches.
Simplified: Through a system of separation of powers or "checks and balances", each of these branches has some authority to act on its own, some authority to influence the other two branches, and is influenced by the other branches.