The nine Justices on the United States Supreme Court recently took up a case about same-sex marriage. The question in Obergefell v. Hodges is whether states are required to license and recognize marriages between two people of the same sex. This post examines the same-sex marriage case and Court in three sections about:
- Public opinion on same-sex marriage (10 graphs)
- Politics and voting on the Court (5)
- Justices, clerks, & opinions about the Court (6)
Part 1: Public Opinion
Opinion Over Time
According to Pew, Americans opposed same-sex marriage by a 57% to 35% margin in 2001. Today 52% support same-sex marriage and 40% oppose it. Pew reports a 95% confidence interval with a margin of error of 2.4%, represented here with error bars.
A Look At The Big Polls
The shift in public opinion is the story of recent polling on same-sex marriage. Made with R, the plot below shows the trend: Approval for same-sex marriage has moved above 50% in multiple polls in the past five years.
Sparklines & Demographics
Here we can see the change broken down by demographics in sparklines. Hover your mouse to learn more.
Attitudes by Generation
Younger generations are more supportive of same-sex marriage. Older generations have shifted their opinions in recent years.
Attitudes by Religious Affiliation
A majority of religiously unaffiliated individuals have supported same-sex marriage since 2001. Support for same-sex marriage has also increased among Catholics, white mainline Protestants, and black Protestants.
Attitudes by Political Ideology
75% of self-described liberals and 62% of moderates support same-sex marriage.
Attitudes by Political Party
64% of Democracts favor same-sex marriage, as do 58% of independents. Most Republicans oppose same-sex marriage.
Attitudes by Gender
Today 55% of women and 49% of men support same-sex marriage.
Attitudes by Race
53% of whites and 42% of blacks support same-sex marriage.
Public Opinion Box Plot
This box plot shows the spread in opinion for each year from 2001-2014. The box shows the distribution of opinions, allowing us to see how values vary within and compare between groups. Note the spreads. For example, moderates reported a 34% approval low in 2004 and a 64% high in 2014. Others have not moved or spread as much (e.g., White Evangelical Protestants changed by 10%). The data below come from Pew polling (see questions here and methodology here).
Part 2: Politics & Why Justice Kennedy’s Opinion Matters
The Court has an average overturn percentage of 0.65% over the last 60 years. This makes sense: the Justices do not need to affirm a case if the finding was the right one. In this case, the Justices are responding to four opposing Federal Court decisions about same-sex marriage bundled into one. This type of lower court disagreement is known as a “circuit split”. The Justices could affirm parts of the lower court decisions–ruling that the lower courts made the right decision on same-sex marriage–or, the Justices could overturn the lower court rulings and make their own.
In this case, analysts believe that the views of Justice Kennedy (pictured above) will take the day in a 5-4 split. In general though, unanimous decisions are about twice as likely as a 5-4 split. For more, see this paper on the “Statistical mechanics of the US Supreme Court.”
Ideological Spectrum of Supreme Court Justices
Another theme of recent scholarship is an ideological shift to the conservative side. For example Martin and Quinn argue that “Between 2005 and 2010, most of the the Roberts’ court five conservative-leaning members became more so.”
Supreme Court Decisions & Public Opinion
Public opinion is less important for a lifetime judge than an elected official. The Court hasn’t always done what is popular with the general public. Support was meager, at best, for decisions regarding interracial marriage, flag burning, and prayer in school.
The Ideology Behind Justice Decision Making
The median Justice casts the deciding vote in a 5-4 split. Kennedy can side with the liberals (Ginsburg, Breyer, Sotomayor, Kagan–Clinton and Obama appointees) or conservatives (Scalia, Thomas, Roberts, Alito–Reagan, Bush Sr. & Jr. appointees). His vote swings the Court, deciding who wins. The graph below shows how each Justice’s ideology relates to the views of the median Justice.
Part 3: The Justices, Clerks, & Public Opinion
Ages, Tenure, & Appointments
Justices serve for life, allowing a President to influence the Court through a nominee well past their time in office (though not always as they hope to). As President Obama noted:
Of the many responsibilities accorded to a President by our Constitution, few are more weighty or consequential than that of appointing a Supreme Court Justice.
This plot shows the average age and length of tenure of the Justices. Both decrease during the years when new justices are appointed (since new justices are typically younger than the existing justices).
Average Age of Serving Justices" style="display: block; text-align: center;">Supreme Court Justices
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The Justices fare well when it comes to nominee approval during confirmation votes. One study’s data shows that state support for nominees sways Senate votes. The solid vertical line indicates the mean level of state support.
The Political Positions of Media
Certain Justices align more closely with certain media outlets, as shown by Ho and Quinn’s figure. The median positions of the justices have been superimposed for comparison in the bottom panel with lines extending into the top plot to compare their views. The gray density presents the unweighted dentisty. The black line presents the density weighted by circulation, with the bump on the right representing the Wall Street Journal. 52% of the papers examined in the study have political positions between the 4th (Breyer) and 6th (Kennedy) Justices. The authors concluded:
In essence, there appear to be four clusters of newspaper positions corresponding to moderate and more extreme liberal and conservative positions. Of particular interest is the fact that even the more moderate papers cleave into left-leaning and right-leaning variants.
Where Clerks Come From
Supreme Court Clerks play a key role in assisting the Justices with opinions and choosing which cases the Court will hear. When the Justices choose clerks, they often do so from feeder judges for whom clerks previously worked at the Federal level. These judges are appointed by Republicans or Democrats, and increasingly serve as direct pipes to similarly-minded Justices. The Times concluded:
The conservative half of the court overwhelmingly hires clerks who served judges appointed by Republican presidents, while the liberal half of the court is more likely to hire clerks from judges appointed by Democrats, a pattern that was not as strong 30 years ago.
Supreme Court Public Approval
The Court, like the decisions it makes, isn’t always popular. A recent Gallup poll reveals that the public approval rating of the Supreme Court has decreased since 2010.
Pace of Decisions
The Court typically releases more opinions near the end of the term in June (OT stands for “October Term”). The plot below shows the average number of decisions released by the Court per year throughout their term. The data was compiled by SCOTUSblog. The end of the term is usually when the Court releases larger decisions. Now all we can do is wait and see.
How We Made These Plots & How You Can Too
Plotly lets you make and embed graphs in your website, blog, or application. It’s easy:
We made this post with a blend of our our web application–where you can upload files and graph data from a spreadsheet–and our APIs for R, Python, & MATLAB. We’re @plotlygraphs, or email us at feedback at plot dot ly. To learn more about how companies are using Plotly Enterprise across different industries, see our customer stories.