With police looking on, Janusz Palikot, the head of the left-wing party Palikot's Movement, took a few puffs from a joint under falling snow in Warsaw on Friday to make their point.
Activists at the gathering said they want the country's laws changed to decriminalise the possession and consumption of marijuana.
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Stelios Alewras, a 26-year-old at the rally, called the act part of a "coming out of smokers of weed".
He said: "I am a lawyer and we want to show that smoking pot is a normal thing like drinking beer."

