The most extraordinary aspect of the new WB network drama “Jack and Bobby” is decidedly subtle. The title characters’ mom, played by Christine Lahti, regularly smokes marijuana. Of course, her son chastises her for it.Obscured by the flashier focus on sex and violence, drug use remains one of broadcast television’s most strictly enforced taboos. The lingering shadow of Nancy Reagan’s “Just say ‘No’ ” campaign, along with controversial efforts by the Partnership for a Drug-Free America and White House drug czars, cast long shadows, keeping primetime a mostly smoke-free environment. Perhaps for that reason, programs on cable lately have caught my eye less for their bare butts and compound words than the freewheeling drug consumption in various series. At the issue’s core lies the conflicted mind-set of a baby boomer generation that continues to just say “Yes,” albeit more discreetly, unless all that contraband coming into the country is smoking itself. The party starts at HBO, where ratings aren’t always high but the characters frequently are. In a recent episode of the Hollywood comedy “Entourage,” the young quartet laments the sudden absence of good “weed” throughout the town. They later meet with a middle-aged mega-producer, whose hard-ass persona melts once they get him stoned. Cocaine blows freely on “The Sopranos,” and one of “Deadwood’s” few sympathetic residents spent much of the first season whacked out on laudanum (the rest were just constantly drunk). Drugs are a major part of life on “Six Feet Under” too, particularly among Claire and her college-age friends. “I’m so much happier when I’m high,” she said in last week’s installment, a line you’re not apt to hear on major-network dramas unless it’s immediately followed by the sound of screeching tires. On “Nip/Tuck” this month, the plastic surgeons stay in a college dorm. When the procedure they perform ends badly, one doctor buys some pot and gets blasted, sharing with his partner and the hooker he’s brought home. Showtime’s upcoming drama “Huff” co-stars Oliver Platt as a pot-smoking, coke-snorting lawyer — a solid citizen by day who indulges shamelessly after hours. Granted, Bob Saget (yes, that Bob Saget) turns up as a chronically wasted sitcom star in a later episode, but that’s played mostly for laughs as opposed to some “Scared Sober!” message. Finally, let’s not forget MTV’s “The Osbournes,” whose wacky family was clearly ingesting more than caffeine and diet pills. What’s most notable about this cable influx is that it has gone on virtually without comment, generating scant protest from interest groups and next to none from viewers. Moreover, given the relatively wide reach of these shows compared with, say, independent film, the public exposure surpasses what’s getting smoked and snorted in theaters. Movies obviously have wide creative latitude, but the subject of drugs is still thorny, especially when teenagers are involved. Motion Picture Assn. of America guidelines state that any drug use by itself mandates at minimum a “PG-13″ rating and in many instances elicits an “R.” By contrast, content ratings are pretty much a joke in TV and thus less of an issue. And while Hollywood and Vine is inevitably presented to the world at large as a modern Sodom and Gomorrah, the truth is people all over are quietly partaking — a reality that applies not just to teens but their parents as well. (Don’t worry, not many kids read the trades, so your secret is safe.) Such matter-of-fact drug use departs sharply from TV’s recent history. Indeed, both the government and broadcasters have promoted the media’s role as a foot soldier in the drug war — highlighted by Congress’ $1-billion allocation in 1998 to support public-service ads of the “This is your brain on drugs” variety. That five-year commitment also resulted in the embarrassing revelation four years ago that networks actually gained financial credit for programs containing anti-drug themes, submitting scripts to the Office of National Drug Control Policy, under then-drug czar Barry McCaffrey, for input and approval. The idea that Big Brother might manipulate episodes of “Chicago Hope” didn’t sit well with groups pushing to revise U.S. drug laws, which unsuccessfully petitioned the Federal Communications Commission to take action. Since then, the public-private collaboration has receded into the background, though few mainstream politicians will weigh in against the efficacy of anti-drug messages — an easy way for broadcasters to curry favor on Capitol Hill. On its web site, the ONDCP’s stated goal is still a sort of “Reefer Madness” model — to ensure that “when drug use is portrayed in entertainment programming, young people see an accurate reflection of its real face — with all its risks and consequences clearly conveyed.” That’s certainly not indicative of the aforementioned cable programs, which, generally flying under the radar, offer a much more realistic and complicated stance toward illicit drugs than the networks do. Drugs aren’t necessarily glamorized, yet nor are they always accompanied by harsh consequences. And wonder of wonders, viewers are responding more with a big ho-hum than shock or outrage — no doubt in part because many functioning citizens are off-hour users. Are the networks, then, tethered by hypocrisy to a dated past? How many viewers would really blanch if a character on “CSI” lit up a joint at the end of a hard day? Does everyone that drinks in primetime have to be a recovering alcoholic? And for true “reality’s” sake, shouldn’t twentysomething dating show contestants occasionally consume something a little stronger than Chardonnay when they pile into a hot tub? The ONDCP’s scare tactics might sound good as a public-policy platform, but America’s complex relationship with illegal drugs suggests it’s naive to think the problem can be mitigated by a few “very special” episodes of “7th Heaven.” Because let’s face it, if that were truly the case, the free-spending government and compliant broadcasters would have blown the smoke away years ago.