Earlier quoted context omitted.
The federal government acts as an oversight body. They should do their job as an oversight body.
So, I would be interested to hear more of your legal theory for this as it could be argued. However in the United States Constitution the 10th Amendment states that all powers not explicitly delegated to the federal government are reserved to the states. Thus establishing the principle of the separation of powers between the federal and state governments as integral to American law. Thus according to the constitution…
> No State shall make or enforce any law which shall abridge the privileges or immunities of citizens of the United States; nor shall any State deprive any person of life, liberty, or property, without due process of law; nor deny to any person within its jurisdiction the equal protection of the laws. [ ... ] The Congress shall have power to enforce, by appropriate legislation, the provisions of this article.
That gives ground for the US government to oversee the states, at least in matters of judicial and policing oversight.