High Times Future

Science Fiction—particularly of the "New Wave" of The Sixties and The Seventies—assumed that increasing liberalization of drugs would continue and that drugs currently banned would become not only legal but also as popular and commonplace as alcohol and tobacco are (or were, now that tobacco is becoming more stigmatized). Usually the drugs in question are "soft" drugs like marijuana and the hallucinogens (particularly LSD) rather than cocaine or heroin; often Fantastic Drugs are part of the mix as well. Some works decide to be ironic and legalize currently illegal drugs, but have alcohol and tobacco banned.

Unlike Government Drug Enforcement, there is no compulsion to take such drugs, and May Contain Evil doesn't necessarily come up (unless a new drug is luring people away from the popular stuff).

Until the 2000s this was somewhere between a Discredited Trope and a Forgotten Trope, what with Drugs Are Bad having been enforced in the United States for several decades. However with increasing number states legalizing marijuana for both medical and recreational use since then, it's beginning to look like a Resurrected Trope.

Contrast with Eternal Prohibition.

Comic Books

 * Transmetropolitan, which leans heavily on the science fiction of this era for inspiration and setting, runs on this trope.

Fan Works
"Harry suddenly felt the urge to hold his hand to his forehead. "Suddenly the Wizarding World makes sense to me. All of the lawmakers are high.""
 * The Wizarding World in The Girl Who Loved, a Harry Potter/Ranma ½/Sailor Moon crossover fic, is a High Times Present, with marijuana use an accepted, if not frequently discussed, part of daily life. (And some wizards use far stronger stuff.)

Literature

 * Bug Jack Barron: Jack's talk show is sponsored primarily by Acapulco Golds, "America's Premium Marijuana Cigarettes" (the book was written when cigarette ads were still legal on U.S. television). Tobacco is illegal.
 * A Clockwork Orange: Mescaline (or a synthesized form) is apparently legal since you can get it added to your yummy glass of moloko.
 * The Eighth Doctor Adventures novel Alien Bodies featured "Cloud Nine: The Original Cannabis Cigarette". As smoked by UNISYC troopers.
 * The Retief stories often referred in passing to lighting up a "dopestick."
 * The Butterfly Kid, written in 1967 and set in 1976, implies that its events lead to a High Times Future. Sadly this wasn't explored in its two sequels.

Live-Action TV

 * Dragnet characters-of-the-week seemed to love this trope. It showed up repeatedly, usually to be met with angry rebuttals by Sgt. Friday.

Western Animation

 * Alluded to in Futurama with a brief gag about a vending machine that sells "Refreshing Crack".