With a series of major decisions overturning decades of precedent, from eroding federal abortion rights to eliminating affirmative action, the U.S. Supreme Court’s legitimacy has been called into question. Among other factors, the perceived politicization of the Supreme Court — whose justices have voted directly along party lines on roughly nine percent of this term’s cases — have led to a sharp downturn in the court’s approval ratings.

This decade has seen a dramatic increase in the percentage of decisions in which votes were split by partisan affiliation, as seen in Figure 1. For this article, partisan affiliation refers to a justice’s self-identified political party, and if not applicable, the party of the president whom they were nominated by.

Theoretically, a judge’s political beliefs should have no impact on legal judgments. Chief Justice John Roberts himself said in a 2016 interview with the dean of New England Law: “We don’t work as Democrats or Republicans.”

Thus to identify any potential correlation between political affiliation and legal judgments, and to quantify exactly how many times justices of the same political party voted in the same direction, The Daily Californian compiled every Supreme Court case on a five-year interval, starting from 1955. Each case in Figure 2 was analyzed to assess the number of justices who voted in opposition to the majority of their colleagues from the same political party.

Although the data displayed in Figure 2 varies over time, judges’ alignment with their parties shows a clear positive trend in the last two decades; justices of the same political affiliation frequently voted in the same manner.

Moreover, about one justice per case deviated from their party’s majority bloc in 1955. Now, justices deviate at less than half that rate, according to Figure 2.

These stark differences in trends are “not surprising,” according to Berkeley Law professor Christopher Kutz, who attributed the data to polarization and ideological screenings of justices.

Compounded with the Supreme Court’s ethics-related concerns and overturning of precedent, approval of the court has diminished, from resting in the high 60s and mid 70s from 1970 to 2000 to 41% in April 2023.

However, reasons for this decline, Kutz said, began much earlier with Bush v. Gore in 2000, when the Supreme Court – split on partisan lines – heavily influenced the U.S. presidential election in what Kutz described as a “nakedly political” move. And according to Kutz, the court’s power of judicial review only holds any weight if it is “less political than the other branches.”

For Jeremy Fogel, executive director of the Berkeley Judicial Institute, the court’s perceived politicization can be tied back to the nomination process for justices.

“The nomination process is so fraught,” Fogel said. “So much money gets spent getting people confirmed or opposing confirmation, or there’s lobbying … They’re being checked thoroughly for philosophical and ideological purity. The process of selecting Supreme Court justices has become so political that it’s hard to say that (the justices) don’t have a predetermined view of things.”

Furthermore, the United States operates under a “common law” system, in which the legal process is to examine the applicable law and the established facts before applying the existing law, Fogel said.

He added that changes from precedent should be “incremental.”

“The common law of approaching (a case) would be to look at, ‘What is this most like?’,” Fogel said. “What does this most resemble? And then you build on the prior cases, but in a very incremental way … You don’t overthrow decades or centuries of the way things have been done.”

Fogel, also a former district court judge in the Northern District of California, said that an analysis of the lower courts would likely find less partisan alignment, due to both their structure and the types of cases heard. When he served, politics were never much of a factor in decisions, he said.

The Supreme Court, however, as a “court of last resort,” often makes decisions with significant national consequences; according to Fogel, this can cause justices’ backgrounds to play a significant role in their interpretation of the facts.

“At the Supreme Court, you really are at the apex — you’re the last word,” Fogel said. “The decisions that they make do have potentially really profound implications downstream. So I think that your mindset, your view of life (and) your life experiences, all of that is really magnified with the court, and so it’s not surprising that you get more uniformity on a partisan basis than difference.”

According to an attorney who has argued several cases in front of the Supreme Court, who wished to remain anonymous due to fear of retaliation, they take into consideration a justice’s judicial philosophy — not their political beliefs — as they develop arguments, now more than ever before. More specifically, this attorney said they have started to emphasize history more prominently in their recent arguments when appealing to the court.

Similarly, Fogel noted that the judicial philosophies now relatively predictably align with political parties. Such philosophies are represented by The Federalist Society, a legal organization advocating for an originalist interpretation of the Constitution, and the American Constitution Society, its progressive counterpart.

“You almost have a two-party system, but it’s not with Democrats or Republicans,” Fogel said. “It’s more so a whole clump of interpretative tools and social values and social networks, and I think all of that makes a difference.”

Yet Fogel disagrees with a “purely political” perception of the Supreme Court as a legislator. Instead, he believes the problem lies not with individual justices, but with the court’s overall structure of nine justices representing approximately 350 million people, a model few other countries have followed.

Ensuring that the expansion of the court remained apolitical would prove difficult, Fogel noted. Gridlock in Congress also forces the court to rule on divisive issues, which further contributes to polarization.

“It’s a tough world to be inclusive and (see) the big picture,” Fogel said. “Things have become very polarized and very results driven. The court makes an effort to be collegial but I think probably beneath that the divisions are really pretty deep.”