Easy, give states the responsibly to prohibit or legalize drugs. Then violate no rights in enforcing the laws. No knock raids, thermal scans of homes, know your customer policies, ect are unconstitutional and should not be used. However, even if all the prohibition did was to keep hard drugs off of store shelves, that would be a great improvement over complete legalization.
Some improvement. Quality control by street thugs is always reliable. Creating business opportunities for lawless thugs is always an improvement. Fostering a business climate where there can be no peaceful resolution to disputes because no rule of law exists is a big improvment.
< /sarcasm>