Only one candidate will really do:
While the Democrats are caving in to Bush's demands on FISA and refusing to put a stop to warrantless wiretapping and much more, Paul is putting out bills like the American Freedom Agenda Act of 2007 (PDF).
This bill would repeal the Military Commissions Act of 2006, restore full habeas corpus requirements, prohibit the use of secret evidence under all circumstances, and end the practice of rendition to other countries to torture terrorism suspects. It also would grant standing to Congress to sue the President over any signing statement that proposes that the President may ignore any provision of the legislation for any reason. An extraordinarily important bill that, sadly, has no chance of passing.