The “opinion” that the Supreme Court may interpret the “Constitutionality” of an Executive Order is itself extra-Constitutional having it’s origin in Marbury vs Madison.
It’s not so much an opinion, as it is a realization that the right of the Supreme Court to interpret Executive Orders according to their Constitutionality is one of the 3 major things that stands in the way between Democracy and a Totalitarian State. After all, if Executive Orders can’t be countermanded in any way, what difference is there between that and a Totalitarian State? It’s also the most important of the three, as it’s the least susceptible to corruption and the one that is closest to the foundation of the State that is the U.S.A., which is the Constitution.
In case you were wondering what the other two things are that stand between Democracy and Totalitarianism; they are the other 2 things that can counteract an Executive Order. An Independent Press, with their ability to give information to the general public about what’s going on; and Congress, by means of the checking power they have over the Executive Branch. Unfortunately, both the Press and Congress have been increasingly corrupted by Partisan Ideology and Private Donors / Owners, so that leaves the Judiciary as the only means to counteract the President that we really have left. If it’s power too were to vanish, Democracy in the United States of America would truly be dead and the country would then be a Totalitarian Regime, if not in name then most definitely in practice.