States' Actions to Block Voters Appear Illegal, from the NY Times:

In addition to the six swing states, three more states appear to be violating federal law. Alabama and Georgia seem to be improperly using Social Security information to screen registration applications from new voters. And Louisiana appears to have removed thousands of voters after the federal deadline for taking such action.

Under federal law, election officials are supposed to use the Social Security database to check a registration application only as a last resort, if no record of the applicant is found on state databases, like those for driver's licenses or identification cards.