Read this: Notably, a statute does not disappear automatically merely because it has been found unconstitutional; it must be deleted by a subsequent statute. Many federal and state statutes have remained on the books for decades after they were ruled to be unconstitutional. However, under the principle of stare decisis, no sensible lower court will enforce an unconstitutional statute, and any court that does so will be reversed by the Supreme Court. Conversely, any court that refuses to enforce a constitutional statute (where such constitutionality has been expressly established in prior cases) will risk reversal by the Supreme Court.
Now answer this question, if there is an answer (If it cannot be answered, return "unanswerable"): What must happen to a statute for it to become unconstitutional?
it must be deleted