S01E12 "The Grass Story"

Maude stands up for her principles when she hears of a teenager arrested for possession of marijuana. Maude convinces her rich liberal girlfriends to picket with her at the police station, and to get arrested themselves as a symbolic move when the police sees that they are also in possession of the drug. It proves to be a challenge for Maude to "score" some, but when she does, she and Walter fight over it.