That said, external forces could force his hand. For example if Canada were legalize marijuana he would be engulfed in debate. The problem for Obama is not only would Canadian boldness flame domestic debate but should Canada have the guts to go through with such a move various European countries (e.g., Spain, Portugal, Italy and the Netherlands) Australia and Latin America, Mexico in particular, would soon follow Canada's led. The international dominos would start falling one by one. This in turn would further embolden domestic proponents, especially those in California.
Politically, Obama's ability to push back would be limited. His hands are tied in ways another leader hands would not be. He freely admits to having marijuana in the past ("I inhaled frequently. That was the point") and his marijuana use is not a part of some redemption narrative, a la George Bush. It was a path he choice not to continue going down. Drug use was never presented as a demon he had to overcome yet alone one he still struggles with the way an alcoholic does with drink. This would leave him open to the charge of hypocrisy. Far more importantly though, the war and drugs, especially with regard to marijuana, has had a profound impact on the African American community in the States. If Obama was to toe the standard line in the face of Canada promising to end the war on drugs, he would be in a world of hurt politically. The African American community would not, of course, abandon him, but they would be unhappy and their unhappiness would have the potential to throw his whole presidency out of whack politically. His whole message of being the candidate of change would be called into question. There is also some evidence that it may be unpopular with Obama's many online supporters.
"On Obama's Change.gov Web site, which was used during the transition period, his staff asked the public to submit new policy ideas. Then the rest of the online community voted on its favorites.The most popular idea, by a wide margin: 'Ending marijuana prohibition.'"http://www.sfgate.com/cgi-bin/blogs/sfgate/detail?blogid=14&entry_id=36162#comments
Finally, there is every indication that Obama is sympathetic to the cause. Obama promised to stop raiding medical marijuana dispensaries during the lead up to the election and he made good on it the other day. This is big. In the month and bit since Obama took announcement 10 states are debating medical marijuana provisions. Once the number of States with medical marijuana provisions (currently there are 13) reaches a critical mass, marijuana will have to be reclassified. It is currently classified as a schedule one drug, i.e., an illegal drug with no medical benefit. A federal show down as to what place marijuana has in US society is, in other words, in the works.
It is also big for another reason. Unlike in Canada, in California, for example, one does not have to be afflicted with a particular aliment to be eligible. A doctor can proscribe marijuana for whatever they see fit. Needless to say, the Bush administration was right to see California's medical marijuana program as a Trojan horse and that is why they cracked down so heavily. The system is ripe for abuse and with medical marijuana users and dispensaries no longer being targeted the medical marijuana industry in California will eventually grow so large as to leave no alternative but legalization.