The idea is the courts look to Congress on what is constitutional and they follow its rulings. A court could only declare a law
ultra vires that is, a law that makes something not delegated to Congress by the Constitution. With judicial review gone, all other laws are presumed constitutional and the courts have a manifest duty to uphold them. Nothing circular about it.
(Denny Crane: "Sometimes you can only look for answers from God and failing that... and Fox News".)
The idea is the courts look to Congress on what is constitutional and they follow its rulings. A court could only declare a law ultra vires that is, a law that makes something not delegated to Congress by the Constitution. Have you read Marbury v. Madison? The plaintiff asked for a remedy that Congress passed, that the Constitution forbid. ANd you say the court is then, faced with that, to choose Congress?