There was another thread about this a few days ago (I'm about to head out the door and can't dig it up myself, but a keyword or headline search should pull it up) in which a lawyer tracked down the relevant court filings in this case, which showed the federal courts very much do have the responsibility of stepping in when the state courts start engaging in massive violations of the most basic rights of the state's citizens ... and have plenty of times throughout American history.
Federal jurisdiction questioned (in case of tax-increase ordered by Nevada Supreme Court)
Those of us who believe in the concept of federalism are in a small minority here on FR, it seems.