The six swing states seem to be in violation of federal law in two ways. Michigan and Colorado are removing voters from the rolls within 90 days of a federal election, which is not allowed except when voters die, notify the authorities that they have moved out of state, or have been declared unfit to vote.
Indiana, Nevada, North Carolina and Ohio seem to be improperly using Social Security data to verify registration applications for new voters.
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.