Prof. Anthony Sebok has a really interesting article up at Findlaw: in Is It Constitutional for the Senate to Retroactively Immunize From Civil Liability the Telecoms That Provided the Government with Information About Customers' Communications? he argues that the proposal to give retroactive immunity to telecom companies who illegally wiretapped their customers may be an unconstitutional uncompensated taking as regards plaintiffs in currently pending claims.
Without doing some research, I don't know the law well enough in this area to form an opinion, but it's intriguing and I'd welcome comments from those who know the area.
