When Edward Norton - who turns 47 today - signed on to play twins Bill and Brady Kincaid in the marijuana drama Leaves of Grass (2009), he had to make a tough decision about getting into character as a pothead. In the movie, Bill Kincaid is a straight-laced, Ivy League professor, but his brother Brady is a hydroponic cannabis grower in Oklahoma who liked to sample his product. So Norton had to decide whether or not - for the sake of authenticity - to have a puff before shooting scenes as Brady.

"I wondered, 'Would being stoned look way better on the film than acting stoned?' " he said while promoting the movie at the Toronto International Film Festival in 2009. But he eventually decided that it would be hard enough playing opposite himself in the movie without being high onset. "The truth of the matter is, making movies is so - especially doing something like twins - you've got to be able to focus. I don't think I could function the way I need to function," Norton said.

However, he did seize on the opportunity to experiment with cannabis advocacy while promoting the movie. While speaking at TIFF, he criticized the irrationality of marijuana prohibition in America.

"Our culture exists with these ridiculous hypocrisies of legalizing one form of controlled substance versus another," Norton Said. "The economic arguments, the arguments in terms of both enforcement and safety [and] rehabilitation, it's something we've got to get around to a more rational place on."

And he didn't turn down marijuana years later when filming another movie. Earlier this month, Seth Rogen said that he and Norton smoked up while unwinding during the production of Sausage Party (2016), in which Norton plays the kosher character Sammy Bagel Jr. It may be that voiceover work as a talking bread requires less concentration.

Here's Norton arguing with himself about academia in "Leaves of Grass."

And here's Norton in the more recent "Sausage Party."