The first one that comes to mind is the Controlled Drugs and Substances Act. In fact, that's the very act that was put in place after the Campbell and Shirose decision. It allows us to traffic in drugs, to import drugs, to export drugs, and so on. The CDSA is excluded from the law enforcement justification, in that the CDSA has its own exemption scheme.
On May 30th, 2006. See this statement in context.