Not sure what role PC plays, as this has always happened, be it drugs or booze, the later is as big or bigger social behaviour issue. There needs to be a zero tolerance for importing drugs, i would make it 20 years if found guilty, take it out of judge's hand and make it mandatory. Plus build small scale prisons 50 to 150 prisoners, where people serving long sentences are kept away from people serving short sentences, easier to control and educate for evenual release. Plus those who will never get out. Start off with basics, room, food, access to books and radio, no TV, games, and let people earn the right for more, hard to cause trouble if you are in a cell 23 hours a day.
Also regular work drug tests, should already be them for police, fire, healthcare workers, train and truck drivers, teachers, etc, start off with the political classes, MPs, Congress and Senate leaders, resign if failed drug test. Make taking recreational drugs too much of a risk, not talking addicts here, more social drug takers, rather like weekend drinkers. if you cut down on the people buying then there will be less need for import.