In the recent debates over the appointments of John Roberts and Samuel Alito to the U.S. Supreme Court, much energy was expended by both left and right on ferreting out their supposed political opinions on abortion, affirmative action and presidential power. Given the history of our highest court, the time might have been better spent figuring out how well Roberts and Alito play with others that is, what kind of personal temperaments they bring to the nine-justice meetings that review our laws. Jeffrey Rosen's The Supreme Court: The Personalities and Rivalries That Defined America, a companion book to an upcoming PBS series, argues that in the long run, personality matters more han ideology. A brilliant justice too rigid to win allies has far less impact than a less brilliant one with effective collegial skills and a supple mind, says Rosen, a George Washington University law professor and legal affairs editor of The New Republic. Rosen's case studies are four rivalries spanning the court's history, including one non-justice: John Marshall and his distant relative President Thomas Jefferson; Oliver Wendell Holmes Jr. and John Marshall Harlan; William O. Douglas and Hugo Black; and William Rehnquist and Antonin Scalia. In each case, Rosen contends, the justices who had the judicial temperament that includes pragmatism, common sense, trust and institutional loyalty Marshall, Harlan, Black and Rehnquist were able to more effectively shape American law. In contrast, the others lived inside their own heads, caring more about abstract ideas than about consensus. Rosen blends biography with clear, accessible descriptions of the sometimes arcane legal cases that illustrate his point. He ends with an interesting recent interview with Roberts, in which the new chief justice seems keenly aware of his predecessors' successes and failures. He worked for Rehnquist, and sees Marshall as a model. Anne Bartlett is a journalist in Washington, D.C.