US DOJ opinion on the legality of VVPAT. (Yes, they are legal provided that some way is also available for the visually impaired to equivalently verify their ballot.)
H.B. 2239, introduced by Representative Holt, and the companion bill S. 1980, introduced by Senator Graham, would "amend the Help America Vote Act of 2002 to require a voter-verified permanent record or hardcopy under title III of such Act,and for other purposes." This and other legislation can be tracked through THOMAS, a source for federal legislative information.