I gave my finals speech on Marijuania legalization. Everybody laughed when they saw what it was about, but I made serious arguments and I think it pulled off well. It's not considered the crazy idea it once was, nor is it only thought that only drug heads who want cheaper access to their habit support it.
Every year Gallup has been polling the issue, the number of people supporting legalization has increased. It's still not a majority or plurality, but if the trend holds there will be a majority within 20-30 years. I imagine young people are far more pro-legalization than older folks.
I am confident that it will happen at least within my lifetime, maybe surprisingly soon.