The 2005 Senate Judiciary Committee hearing on the nomination of John Roberts to be chief justice is best remembered for his oft-quoted assertion that “judges are like umpires.” Few remember the line that preceded it: “A certain humility should characterize the judicial role.”

The Supreme Court will soon complete its ninth term with Roberts at the helm. In “Uncertain Justice,” Harvard Law School professor Laurence Tribe and his former student Joshua Matz find much to analyze and explain in the “wondrous complexity” of the Roberts court. Their well-told story is not one of judicial modesty, however, either for the aspirations of the Roberts court or for its impact on American life.

From the Affordable Care Act to affirmative action to campaign spending to gun owners’ rights, the story of the Roberts court is one of grappling with many of the major issues of the day and resolving them in ways that assert the major role of the Supreme Court in our lives. For example, when the authors describe in detail the 2012 ruling upholding the individual mandate for health insurance in the Affordable Care Act, they note that five conservative justices who rejected regulating interstate commerce as a basis for the law “signaled a willingness, perhaps even an eagerness, to resume a judicial role in limiting federal economic regulations that the court had largely abandoned in 1937.” Later, referring both to the health-care ruling and two decisions involving federal regulation of sex offenders, Tribe and Matz maintain that these cases “mark a new and momentous development in conservative efforts to articulate judicially enforceable constitutional limits on Congress.”

These descriptions of an ambitious court by no means amount to a liberal screed; far from it. The strength of the book is its painstaking explanation of all sides of the critical cases, giving full voice and weight to conservative and liberal views alike. In a well-written and highly readable narrative, the book patiently provides background, context and insight on important constitutional issues.

The Roberts court has matured enough, after more than 600 decisions, to merit significant attention. A year ago, the National Law Journal’s chief Washington correspondent, Marcia Coyle, produced “The Roberts Court: The Struggle for the Constitution ,” and last fall Tribe’s Harvard Law School colleague Mark Tushnet delivered “In the Balance: Law and Politics on the Roberts Court.” Tribe and Matz’s book is a welcome addition to the group, although it may try too hard at times to create a sense of drama about constitutional law. In the prologue, the authors describe the story of the court and the future of the country as one “marked by uncertainty, but one all the more thrilling for its lack of a predetermined outcome.” “Thrilling” may not be one of the first words that comes to mind when most people think about the Supreme Court. Trying to create suspense in another passage, the authors declare that although the Affordable Care Act may have survived, “liberty’s soul remains up for grabs in the Roberts Court.”

‘Uncertain Justice: The Roberts Court and the Constitution’ by Laurence Tribe and Joshua Matz (Henry Holt )

But occasional overwriting may be excused. The common-sense tone that prevails in most of the book is a tribute to the mastery of the Supreme Court by Tribe, a keen observer of the justices and of constitutional law for more than four decades. For many years his insights about constitutional law dominated the field in a treatise that he first published in 1978 and then scrapped in 2005, leaving a third edition unfinished. He attributed cessation of the work to profound uncertainty about the future direction of major constitutional doctrines.

There is an irony, then, in the title “Uncertain Justice” and its focus on major cases in which constitutional principles are being revisited and debated by the current justices. Although it is common to think of the court as divided along predictable ideological lines, the authors present a different picture, explaining that they use “uncertain” in their title because the court’s decisions “are beyond precise calibration and exact prediction.”

Tribe and Matz describe a court “deeply torn” and in flux over free speech, with some restrictions upheld and others overturned. The result is a “skipperless” and “drifting” approach. On rulings protecting the right of individuals to own guns under the Second Amendment, the authors suggest that the court has taken a “narrow and cautious” approach that, if followed in future cases, “will leave the democratic process broad latitude to address gun-related danger effectively and creatively.” On the decision invalidating the federal definition of marriage in the Defense of Marriage Act, the authors observe that the future direction of the same-sex-marriage issue in the Supreme Court is “uncertain.” Referring both to same-sex marriage and to decisions curtailing the use of race in affirmative action and in elementary and secondary school placements, Tribe and Matz declare that “equality is an explosive principle on the Roberts Court,” with the justices disagreeing “on where we have been, where we are and where we should go.”

Tribe and Matz leave little doubt about the high stakes riding on Supreme Court decisions. “The justices can frame the way we live,” they write. In the end, the authors want readers to see at least two kinds of uncertainty. One is the uncertain outcome of major issues still to come before the court; the other is the uncertain impact of certain decisions already rendered. But there is one facet of the Roberts court where Tribe and Matz find real clarity: the shrinking availability of judicial relief. “One of the defining features of the Roberts Court,” they write, is “its willingness to leave plaintiffs and criminal defendants to whatever justice they can find beyond its doors.”

Stephen Wermiel teaches constitutional law and a Supreme Court seminar at American University’s Washington College of Law and is a coauthor of “The Progeny: Justice William J. Brennan’s Fight to Preserve the Legacy of New York Times v. Sullivan.”

UNCERTAIN JUSTICE

The Roberts Court and the Constitution

By Laurence Tribe and Joshua Matz

Henry Holt. 401 pp. $32