[zeveb]

It would be unconstitutional for the Congress to pass laws taking full oversight of state and local police (it's not one of the Congress's enumerated powers, and per the Tenth Amendment 'The powers not delegated to the United States by the Constitution, nor prohibited by it to the States, are reserved to the States respectively, or to the people.').

Sometimes police are found to have violated federal civil-rights law, but that is a bit of a sketchy backdoor.

The Right Thing would be for each state to create such a commission, and for the Congress to create one for federal law-enforcement agencies.

[dragonwriter]

Actually, ensuring that states provide equal protection of the laws to all persons, that states do not deprive persons of life, liberty, or property without due process, and that states do not abridge the privileges and immunities of US citizens is an enumerated power of Congress; see the Fourteenth Amendment, particularly sections 1 and 5.

[zeveb]

You make a good point. I suppose one might be able to justify such a commission on that basis (although that itself indicates the problem with the post-Civil War order).