In many Dystopian settings, The Government forces everyone to take psychoactive drugs. Maybe it's to keep them peaceful and non-aggressive so they don't hurt each other (or more cynically, to keep them too mellow and torpid to have the energy and desire to revolt). Maybe it's birth control pills to keep the population in check. Maybe it's outright Mind Control. Maybe it's Super Serum to keep their Supersoldiers, well, super. But those who refuse to take the drugs are put into prison, or worse. Or perhaps it's just strongly encouraged to take the drugs, with only outright troublemakers forced to take the drugs whether they like it or not.