Because the Native Americans were not introduced to European diseases on their own homeland.
Their immune systems were exposed to European Diseases that they never were in contact with before, which caused sickness. Without today's medicine, they were basically helpless and left to die from the exposed diseases.
The thing that the state could do if it disagreed with the national law. the state could have a special conviction to nullify the law.
D) a decline in U.S. union membership.
