Q58. "I would like to know what the President can
and cannot accomplish via an Executive Order. If Congress has NOT passed laws
that mandate certain Administration policies which means that those policies
are merely the result of interpretation of existing law then can the President
issue an Executive Order that amend those policies, assuming the new policies
do NOT contravene existing law. Would this be constitutional?"
A. An Executive Order can be issued by the President at any time to modify
how any part of the Executive Branch does its job, or to modify how a law is
implemented, if such power has been vested in the President by another law.
For example, I did a search on executive orders with the word Naval in them,
and found one that transferred control of the Midway Islands from Navy control
to Department of the Interior control.
Another establishes an Emergency Board to mediate disputes among various
railroads, as provided in a section of the U.S. Code.
It is certain that an Executive Order could be unconstitutional.
I'm not sure I get your example, but from the executive orders I have read, the
power vested in the President by the Constitution or by existing law is what is
used as the basis for the ability to issue the order.