Is there really a majority in favor of marijuana legalization?

Ever feel like you're experiencing deja vu? I'm sure it's happened to those of you who have smoked cannabis – you know, grass, marijuana, or, as the cool kids might say, weed. And while I'm not personally smoking the stuff, I get the same feeling when talking about marijuana polling.

It was big news Tuesday when Gallup released a poll showing that a record high 58% of Americans believe marijuana should be legalized. But the proof that a majority of Americans are in favor of cannabis legalization is, as I wrote earlier this year, simply not there yet. Take the Gallup poll, and the trend in it over the past few years. It looks like a rollercoaster – 46% thinking it should be legal in 2010, 50% in 2011, 48% in 2012 and 58% in 2013. I tend to doubt support jumped 10 percentage points in one year. Usually trends on social issues are more linear, as with gay marriage.

A look at other polling confirms that Gallup's survey, and the rapid change it showed, has a better chance of being an outlier than not. Of the three other polls taken this year, only Pew's found a majority who believe use of marijuana should be made legal. Pew's 52% was far less than Gallup's 58%, and it, at least, followed the more linear trend of support building slowly over a few years that one might expect.

The other two polls conducted in 2013 actually found that more people than not wanted recreational use of marijuana to stay illegal. A survey conducted by Fox News had the number in favor of legalization only at 46%, with 49% opposed. And a Public Religion Research Institute* survey matched the Fox News poll, with 45% in favor of marijuana legalization and 49% opposed.

Indeed, a look at the broader range of polling suggests that over the past few years, public opinion on legalizing marijuana has stayed mostly steady:

ABC News/Washington Post (2009-2012): 46%, 46% and 48%

Angus Reid (2009-2012): 53%, 52%, 55%, 52% and 54%

CBS News (2009-2012): 41%, 31%, 41%, 44%, 40%, 45% and 47%

The important finding to take away here is that while some polling has a majority in favor of marijuana legalization and some doesn't, there isn't much change in the numbers found by each individual pollster; what variation there is tends to be what one would expect from sampling error.

For me, the most important poll on the subject of marijuana legalization is the General Social Survey. It's not a poll that most in the public have heard about, but it's well known within academic and research circles. Conducted by the University of Chicago every couple of years, the poll has a near 70% response rate compared to only about 10% for most public surveys. It ensures that tougher-to-survey demographics, like African Americans and Latinos, are better polled.

The 2012 General Social Survey (pdf) demonstrates, like most other polling, that support for weed legalization is up over the past 25 years, yet shows no clear trend over the immediate past. In fact, the percentage who wanted weed to be made legal actually dropped from 44% in 2010 to 43% in 2012. And 43% is, of course, not a majority.

That said, it seems to me that we're likely heading towards a society in which marijuana will be legal. All pollsters have support for marijuana legalization jumping by about 20 points over the past 20 years. A few more polls that look like the ones from Gallup and Pew will convince me that a majority favor marijuana legalization now.

* Yes, its numbers are good, even if the name would imply a bias against weed.