If you are a political junky, there is no better place on the web than pollster.com. You not only get great polling data--you get in-depth understanding of various survey methodologies. How cool is that!! (At this point, my loving wife informs me that I am not a political junky--I am a political geek. Sigh)
In any event, as an example of the excellent work you can find on this site, is Charles Franklin's detailed analysis of the changing views of the public toward gay marriage.
First, Franklin offers this analysis of the changing views of the public on gay marriage:
[i]n 1985 82% of the public opposed same sex marriage, while only 11% supported it. By the early 1990s, when the data become richer, opposition was at about 65% while support stood at about 28%. Congress passed, and President Clinton signed, the federal "Defense of Marriage Act" in September 1996, but public opinion trends seem not to have noticed at all, neither rising nor falling around that time. By the week of the California ruling, May 15, 2008, opposition had declined to about 55% while support had grown to 40%. The net effect of some 16 years of public debate was a 10 point decline in opposition and a 12 point rise in support.
But that trend was not uniform. The Massachusetts ruling, and the 2004 election campaign, coincided with a sharp, if relatively short term, disruption of the previous slow but steady decade long shift of opinion. The Massachusetts Court decision placed the issue squarely on the public radar, and the 11 state ballot proposals in the 2004 election created the setting for public debate and political exploitation of the issue.
During the year from November 2003 to November 2004, opposition to same-sex marriage rose by five points, from 55% to just over 60%. Meanwhile support fell by about eight points, from 38% to 30%, then rebounded by a point or so by election day. (These shifts slightly predate the Massachusetts decision, probably reflecting the increased visibility of the issue prior to the Court's ruling.) The impact of these shifts and of the 11 referendums that were passed on the presidential election remains debatable. Initial punditry credited the referenda with helping defeat John Kerry, especially in Ohio. More careful subsequent analysis doubts much of an effect, however.
These sharp shifts in trend reversed direction immediately following the 2004 election, but took more than two years to return to pre-2004 levels. Support returned to 2003 levels in mid-2007 while opposition has only now, in May 2008, declined back to where it stood in mid-2003. Despite this slow recovery from the 2004 "shock", the 2005-08 trend lines make it clear that public opinion returned to its previous trajectory of slowly rising support and declining opposition in the aftermath of 2004. It is also interesting that the 2006 elections, with 8 states voting on referenda, made no discernible difference to the post-2004 trend. In part this may reflect the more limited number of states, but it also reflects some decline in the saliency of the marriage issue.
Franklin then addresses the issue of whether the California decision will cause, like the Massachusetts decision, a down-turn in opposition to gay marriage:
The 2003-04 data clearly show the potential for sharp changes when the marriage issue becomes extremely salient. That the fight will take place in the most populous state in the Union also guarantees national exposure. However, the fact that most states have already settled this issue through law or amendment, and that only three states (so far) are on track to have proposals on the ballot, means that the issue is more localized than it was in 2004.
Opinion now is not much different from where it was in mid-2003, so a similar reaction is possible but there may be an element of "been there, done that" as well. The novelty of the issue is surely much reduced now than it was five years ago, though the record of referenda passing in 7 of 8 states in 2006 certainly demonstrates that opposition to same-sex marriage remained strong even in a very pro-Democratic election year. (Wisconsin, for example, reelected a Democratic governor and flipped a House seat to the Democrats but also modified its constitution to ban same sex marriage or anything substantially equivalent to marriage.)
Finally, Franklin notes that while the public is opposed to gay marriage (by declining margins), this is not true of marriage alternatives such as civil unions, and when you combine support for civil unions with that of gay marriage, there is a winning majority for some form of recognition for long-term same sex relationships:
When the "civil unions" option is added, opposition to gay rights drops significantly from about 55% to 40%. Likewise, support for gay marriage drops from 40% to 29%. The "comfortable" middle ground is then some 26% who are willing to support civil unions so long as they fall short of "marriage".
This "half a loaf" approach is acceptable to only some in the gay rights community, but it is precisely the politically acceptable position that Democratic politicians think can move them from the losing side of public opinion to the winning side. If we add supporters of marriage to supporters of civil unions, we get the chart below.
This is now a near mirror image of the balance of opinion in the first chart. Now about 53% support either civil unions or marriage, and a minority of 40% oppose any legal rights for gay and lesbian couples. By assuming supporters of marriage will not punish them for the expedient support of only civil unions, Clinton and Obama (and many other Democrats) have tried to turn a losing position into a winning one.
Read it all here.
So what does this all mean? In the short-term, it will be a close call whether the public in California will support a constitutional amendment to ban same sex marriage. (But remember that the California Legislature twice adopted same sex marriage.) In the not so distant future (in about a decade), however, if these trend lines continue, public opinion will support same sex marriage.