His Barron decision does not, as it, in effect, says that state governments are not subject to the laws/principles of our BOR's. This defeats the whole purpose of having a written Constitution.
It actually doesn't defeat the purpose of the Constitution. The Constitution was written to create a federal government, and to define its powers. Marshall's ruling was consistent with that purpose. He wasn't saying that states have the power to interpret the Constitution as they see fit, nor did he say they weren't subject to the law. He was saying that the law didn't say what the plaintiff in error claimed it said. That's all.