I think you're talking to the wrong guy about that. I would have no problem whatsoever with a decriminalization of drugs, and besides that, I think that the federal government should have just about zero power to conduct criminal investigations; I think just about all federal criminal law is unconstitutional and unsupported by a enumerated power.
Criminal law is a state matter. While I would still say that my local state trooper should have no right to look at my library records, it would be less offensive than the Feds.
Spend some time in Amesterdam and tell me if you have the same opinion about legalized drugs. On the criminal law issue, sure the federal government has expanded way beyond what the framers could have imagined, but they did have federal criminal law, even back in the days of Jefferson.