To figure out the answer to this, you must first know what McCulloch vs. Maryland was about. So what happened was that Congress created a national bank called the Second Bank of the United States. The state of Maryland actually tried to impose taxes and literally tax the federal bank. James McCulloch, who was the leader of the bank's branch in Baltimore, refused to pay the tax, and so the case came before the Supreme Court. The Supreme Court ruled in favor of McCulloch. This meant that state governments could not tax the federal governments or tax extensions of the federal government (like the national bank).