The executive only has discretion if the law says they do. If the law says they must or shall do something, they must do that thing. If it says they MAY do some

The executive only has discretion if the law says they do. If the law says they must or shall do something, they must do that thing. If it says they MAY do something or otherwise explicitly gives them discretion in making a decision, then yeah, they have that discretion But it's not a given that they can just decide what laws they will or will not enforce or follow