The executive doesn’t pass laws. Congress created the Department of Defense. Only Congress can rename it. The executive being elected is irrelevant to this point. The Constitution actually matters.

You are. Congress could stop this right now if they wanted. That they aren’t is of course a problem, but that’s very different than saying the system of checks and balances doesn’t exist. The latter is giving the executive power it doesn’t have.

This isn’t how this works. Laws don’t change just because the executive decides it’s going to ignore them. https://www.law.cornell.edu/uscode/text/10/111

Only Congress has the authority to change the name. Given they *haven't* authorized it, the name remains DoD. It doesn't work the other way around.

Let me state this very simply: executive agencies have only the power granted to them by Congress. So yes, all actions taken by an executive agencies are bound by the law. Anything else is ultra vires and of no effect.