Separation of powers?

The Environmental Protection Agency (EPA), for example, like most significant federal bureaucratic agencies, holds a combination of legislative authority (it makes rules and regulations with the force of law), executive authority (it enforces those rules and regulations), and judicial power (it interprets the rules and regulations, decides disputes involving its rules, and levies punishments when necessary). Critics argue that such consolidated power undermines the principle of separation of powers, so undermines democratic values. What do you think?