"Let's see, they can now smoke weed in CA, but it is illegal to own/purchase it? What has my brained failed with here...hopefully I have missed some facts."

Pic, as far as I know, smoking weed is still illegal in CA (hard to believe), but not in WA or in CO, perhaps you got your initials mixed! One would still be violating Federal law in WA or CO by smoking, but I get the feeling there won't be much enforcement of that law in either state.

By the way, during Prohibition, it was not illegal to drink booze, but it was illegal to manufacture, transport, warehouse, and sell it! My understanding is that the government did not want to have to be arresting a bunch of "high society" people, including, no doubt, many in the government! You never saw a bunch of poor stiffs in the speakeasies as depicted in the TV and film industries.