Can a State Eliminate the Intent Requirement for Drug Delivery Laws?

There is an interesting fight brewing in Florida about whether a State can constitutionally eliminate the intent requirement from drug laws and make it a crime to unknowingly deliver a controlled substance. Florida has tried. If a Fed Ex delivery person unknowingly delivers a package containing drugs to home, he is guilty of a serious felony. The National Association of Criminal Defense Attorneys is lead amicus in a challenge to this practice. In addition to standard authority, the NACDL makes an interesting international law argument that intent is required under the law of nations.