The Supreme Court’s recent decisions on affirmative action, voting rights and gay marriage have sparked a heated debate about discrimination in America and the Court’s role in deciding the most important issues of the day.

In Fisher v. Texas the justices implicitly upheld affirmative action and sent the case back to the lower courts to apply the law more specifically. In Shelby County v. Holder the Court struck down one part of the Voting Rights Act (VRA) and implicitly invited congress to be more specific with the law. In United States v. Windsor the justices struck down the federal Defense of Marriage Act (DOMA) but said that the appellants in Hollingsworth v. Perry did not have the legal authority to bring the case to the Court.

While each of these cases was certainly important to the litigants, and for the development of the law, they may be more important for what they did not do: abolish affirmative action, overturn the VRA, and declare a fundamental right to gay marriage.

In this sense, the justices ruled far more narrowly than they could have and at once both pleased and frustrated liberals and conservatives alike. What accounts for these relatively narrow decisions?

The simple answer is that Chief Justice John Roberts Jr. has dramatically influenced constitutional decision making on the Court.

In his confirmation hearings and subsequent lectures and interviews, Roberts has emphasized the importance of judicial modesty and expressed a desire to see the Court rule on cases in narrow ways that do not have far reaching effects. This approach to decision making has been labeled “judicial minimalism” by judicial scholars. Roberts has largely transformed the Court from one where broad, sweeping pronouncements were the rule to one where they are the exception.

Instead, narrow, minimalist rulings are now the order of the day. In each case, Roberts voted for a narrow position and his view prevailed in three of the four decisions. In the case where it did not—Windsor—he drafted a dissent emphasizing that the Court’s holding was limited.

In Fisher the Court declined to abolish affirmative action in university admissions and instead left in place the Court’s precedents on the issue and directed the lower courts to apply the standard from those cases more rigorously. Furthermore, the majority did not uphold affirmative action broadly as the dissenters in the case urged. The Court acted similarly in Shelby County invalidating Section 4 of the VRA that established the formula and criteria for determining whether a state or voting district would be subjected to the “preclearance” provisions of Section 5 of the VRA. States who meet those criteria must submit any changes in voting procedures or voting districts for approval by the Justice Department before those changes can go into effect.

The majority reasoned that because the criteria have remained the same since the 1960s and 70s, they may not reflect current conditions in the states that have been subjected to the preclearance provisions for decades now.

However, the Court did NOT strike down Section 5 of the Act which would have been far more dramatic and far-reaching. Roberts’ majority opinion in the case was limited to Section 4, and it expressly showed deference to congressional authority over the broader policy area. Indeed, the opinion is clever because he is able to show deference to the legislative branch at a time when the current state of affairs in Congress makes it unlikely that they will take up the invitation to rewrite Section 4.

In Windsor, the Court struck down a federal law that did not allow federal recognition for gay couples who were legally married on the state level. The law in effect denied federal marriage benefits in taxes, estates, and related matters. In Perry, the justices said that because the state declined to participate in the case and a private party instead brought the appeal, the case could not be decided by the Supreme Court.

What the Court did not do in the gay marriage cases is to declare a fundamental right to gay marriage as they did in Loving v. Virginia (1967) with regard to interracial marriage. In Loving the Court said that the Equal Protection Clause forbids states from restricting marriage on the basis of race.

The Court could have made a similar holding in Perry but chose to avoid that issue altogether by deciding the narrow question of whether or not the party bringing the suit had the legal status to do so.

Consider Roberts’ dissent in Windsor: “I write only to highlight the limits of the majority’s holding and reasoning today, lest its opinion be taken to resolve … a question that all agree, and the Court explicitly acknowledges, is not at issue.” Instead of the broad question of a fundamental right to gay marriage that states may not restrict, the narrow issue for the Court was only whether those legally married in a state can be denied federal marriage benefits. Kennedy’s majority opinion in Windsor states: “This opinion and its holding are confined to those lawful marriages.” Thus, Windsor has no effect on states that forbid gay marriage.

In short, despite all the hyperbole about these cases in the press, the Court took a narrow path on all three issues: affirmative action, voting rights, and gay marriage.

Yet, we have seen the influence of Roberts on Supreme Court decision making in constitutional cases throughout his tenure. For example, last year, in National Federation of Independent Business v. Sebelius, Roberts wrote the majority opinion that upheld the individual mandate provisions of the Affordable Care Act (ACA), but only because they could be considered a tax and thus valid under Congress’s taxing power. While effectively showing some deference to Congress, he also managed to limit federal commerce power and protect states from losing Medicaid funding if they didn’t satisfy coercive conditions placed on them under the ACA.

These decisions are not isolated incidents or simply anecdotal evidence that Roberts is delivering on his pledge to show judicial modesty and exercise judicial minimalism.

In an ongoing research project, we have analyzed the constitutional decisions of the Roberts Court and compared them with the last decade of decisions handed down by the Rehnquist Court. We have categorized those decisions according to how broadly or narrowly the Court upholds or strikes down federal statutes.

Since Roberts has assumed the chief justiceship, the trends are clear. Our analysis of data from 1994 to 2011 shows that that the Roberts Court either upheld the constitutionality of federal laws on narrow grounds or narrowly struck them down as applied (as opposed to broad, facial invalidations) almost 68% of the time compared to only 38% during the Rehnquist Court.

Similarly, the individual votes of the justices have shifted from broader holdings under Rehnquist to more narrow ones under Roberts for each of the justices serving on both Courts. For example, Justice Antonin Scalia went from ruling narrowly 57% of the time under Rehnquist to 71% under Roberts. Justice Anthony Kennedy increased his narrow rulings from 59% to 75%. Justice Ruth Bader Ginsburg only cast narrow votes in 48% of the cases under Rehnquist but has ruled narrowly 74% of the time under Roberts. Justice Stephen Breyer has increased his total from 45% to 82%. Justice Clarence Thomas is the only exception as his narrow votes have been fairly consistent throughout at 65%.

In short, Chief Justice Roberts has had a dramatic effect on his colleagues’ behavior. He has been quite successful in achieving his stated goal of leading the Court to narrower, minimalist decisions.

The implications for policymaking cannot be overstated. Narrow, minimal decisions allow those in the policymaking process room to maneuver. Legislatures and executives can more easily respond to the Court’s decisions by amending laws and implementing them differently.

The Shelby County decision is a prime example of this effect. Commentators have noted that President Obama and Congress can respond to the Court’s decision by attempting to revise the Section 4 criteria of the VRA. Whether they choose to remains to be seen. Had the Court ruled more broadly and struck down Section 5, both the President and Congress would have no such freedom to act.

In the gay marriage cases, the Court has left the issue to be decided on the state level. In this sense, the judicial minimalism being practiced by the Roberts Court places the justices at the center of an ongoing dialogue with elected officials and the American people–a very different position from where they were under Chief Justice Rehnquist.

Artemus Ward and J. Mitchell Pickerill are Associate Professors of Political Science at Northern Illinois University.