Beau Kilmer, Codirector of RAND Drug Policy Research Center and coauthor of Marijuana Legalization: What Everyone Needs to Know, told BI that what happened on Tuesday "was really groundbreaking. No modern jurisdiction has removed the prohibition on commercial production, distribution and possession of marijuana for non-medical purposes. Not even Holland."

Kilmer explained that while many people think marijuana is legal in Amsterdam, the governments have simply decided on a formal policy of not enforcing the law against small transactions.

"If you're over 18 you can walk into one of those coffee shops and buy up to five grams," Kilmer said. "Think of it being legal in the front door. However, it's illegal to grow it, distribute it and sell it to the coffee shops in the Netherlands—so it's actually illegal in the backdoor."