SCOTUS has no power. All they have is Opinions. That's it. Nothing more.
If The Founding Fathers had wanted SCOTUS to have actual 'power', they would have given them an Enforcement Arm. But they have none. All they have is Opinion.
Once they give an Opinion, they have to ask the Executive Branch to enforce it. Opinions, without the power to enforce them are nothing more than suggestions. And that's all SCOTUS has. Suggestions.
The Legislative and the Executive Branches can ignore SCOTUS any time they're in the mood