There’s encouraging news in recent polls about two civil liberties issues — marriage equality and marijuana legalization — and it’s got some observers talking about “tipping points” and “a bandwagon effect.”

Take marijuana: A poll released yesterday by Zogby and the O’Leary Report found that 52 percent of respondents would favor legalizing marijuana, with 37 percent opposed. That’s the first poll I’ve seen that found a majority in favor. (The poll was released in a full-page ad in The Hill newspaper on May 6 and does not appear to be online. It had a sample of 3,937 voters from the 2008 election, weighted to reflect the election outcome. Presumably it was an online poll, but if it had any bias it appears to be in a conservative direction: other results included 57 percent support for the “tea parties,” 71 percent opposition to new gun control laws, 57 percent opposition to cap-and-trade, and 53 percent opposition to legislation that would pressure radio stations to provide “diversity.” Of course, it’s kind of scary that only 53 percent of respondents opposed ideological censorship of radio.)

Whatever you think of that poll, it’s not the only one. In February, Nate Silver posted a chart of polls on legalization, showing a slow but steady rise, up to about 40 percent. A Field poll in April showed that 56 percent of Californians support legalizing and taxing marijuana, the first time Field had ever found a majority in favor. The poll was largely on budget issues, and voters may have been desperately searching for new revenue sources other than general tax hikes. Also in April an ABC News/​Washington Post poll found 46 percent of respondents in favor of legalizing the use of small amounts of marijuana, an all-time high in that poll.

The New York Times points to other signs of change on the marijuana front: Pot has become essentially legal for anyone in California who can tell a medical marijuana clinic that it would make him feel better. Attorney General Eric Holder has said that the federal government would back off its attempt to enforce the federal laws against medical marijuana in the 13 states that have legalized medical use. The threats to prosecute Michael Phelps for a bong hit were widely ridiculed. These developments have led Andrew Sullivan and CBS News to speculate about a “tipping point” for change — at last — in marijuana prohibition. Just this week, California governor Arnold Schwarzenegger said there should be a major study of the possibility of legalization.

Meanwhile, TPM and AOL’s PoliticsDaily also see a tipping point for marriage equality. A majority of New Yorkers now join Gov. David Paterson in supporting same-sex marriage. That same ABC News/​Washington Post poll finds that “in 2004, just 32 percent of Americans favored gay marriage, with 62 percent opposed. Now 49 percent support it versus 46 percent opposed — the first time in ABC/​Post polls that supporters have outnumbered opponents.”

Over the past decade many states have passed bans on gay marriage, a fairly redundant exercise since none of those states had or were about to have marriage equality. But suddenly, since the narrow victory for California’s Proposition 8 in the 2008 election, and really within the past month, same-sex marriage is picking up steam. The Iowa Supreme Court ruled unanimously that excluding same-sex couples from marriage violates the Iowa Constitution’s equal protection guarantee. The Vermont legislature passed marriage over the governor’s veto. The Connecticut legislature and Republican governor Jodi Rell affirmed the state court’s ruling for marriage equality. Maine governor John Baldacci signed into law a freedom-to-marry bill overwhelmingly approved by the Senate and House. The D.C. Council voted 12–1, with only well-known marriage defender Marion Barry in opposition, to recognize same-sex marriages from states that approve them. Both houses of the legislature in crusty libertarian New Hampshire have passed a gay marriage bill, which now awaits a decision by Democratic governor John Lynch. Marriage advocates are optimistic in New Jersey.

Some of these laws may be overturned by Congress or by popular vote. And some 30 states have constitutional bans on gay marriage, limiting the opportunity for progress in most of the country. But one of the striking things about the rapid succession of votes is the lack of public opposition. Conservatives have been remarkably silent, perhaps because some of them genuinely do feel less outrage about legislative action than about “judicial tyranny,” and perhaps because opposition to gay marriage is getting to be embarrassing among educated people. My former colleague Ryan Sager, best known for his book The Elephant in the Room: Evangelicals, Libertarians and the Battle to Control the Republican Party, argues in his new Neuroworld column “that we may be starting to see a ‘bandwagon effect’ that will significantly increase support for gay marriage in the next few years.” He cites Nate Silver’s chart on rising poll support for marriage equality and notes that support for gay marriage is rising much faster than support for interracial marriage did in an earlier era. Zogby asks the same question: Has the tide turned for same-sex marriage?

One striking point in all these polls, of course, is the age difference. That ABC News/​Washington Post poll “showed just how much of the movement is occuring among younger voters. Support for gay marriage has grown somewhat among voters over age 65, from 15 percent to 28 percent, but six in 10 remain strongly opposed. Among those under 35, though, two-thirds support it, up from 53 percent in 2006, and nearly half support it strongly.” And “[s]upport for legalizing small amounts of marijuana for personal use is nearly twice as high among young adults (57 percent of those under 30) as seniors (30 percent), with middle-aged Americans split about evenly.” Obama carried young voters by 2 to 1. If the Republicans get out front on opposing marriage equality and marijuana reform, they can make that a permanent Democratic majority.

By the way, that much-discussed ABC/Post poll also showed declining support for gun control. Trapped in the liberal-conservative paradigm, ABC discusses that point this way: “Other views tilt more to the right. Just 51 percent in this poll support the general principle of “stricter gun control laws,” about the same as last September (50 percent) and down sharply from its peak, 67 percent in mid-2000. The 48 percent now opposed to gun control is the most in polls dating to 1989, and the number “strongly” opposed, at 36 percent, its highest in that time. ” Those of us who have escaped the liberal-conservative paradigm recognize that the right to bear arms is also a civil liberty, and it’s entirely consistent to support marriage equality, marijuana legalization, and the Second Amendment.

The “shift to the left” that we seem to observe on economic policy is depressing to libertarians. But that’s mostly crisis-driven. When the results of more spending, more taxes, more regulation, and more money creation begin to be visible, we may see the kind of reaction that led to Proposition 13 and the election of Ronald Reagan at the end of the 1970s. Meanwhile, this cultural “shift to the left” is far more encouraging. And don’t forget, at 90 days into the Obama administration, Americans preferred smaller government to “more active government” by 66 to 25 percent.