As marijuana advocates in Canada take part in 4/20 cannabis culture demonstrations today, they know pot-smoking events in the not-too-distant future could actually be legal.

But when the Liberal government makes good on its campaign promise to legalize marijuana, there are bound to be many questions about life in a pot-permissive Canada that are more about social norms than laws. In the U.S., Colorado and Washington have already lifted their prohibitions on weed, leaving American etiquette experts with a new frontier to address. 

CBC News asked Lizzie Post, great-great-granddaughter of renowned etiquette expert Emily Post and co-president of The Emily Post Institute, to weigh in on marijuana etiquette.  

"I think where it goes wrong is when people just assume that because it's legal they can do it anywhere, anytime and it doesn't matter," she said. "All the rules of good etiquette still apply." 

Marijuana at work? Probably not. 

Companies should develop policies around marijuana use as soon as legalization looks like it will...