THE biographer of a judge, even a great one like Oliver Wendell Holmes, encounters several hurdles in producing a lively account for the general reader. Liva Baker gracefully negotiates the obstacles in this masterly portrait of a legendary Supreme Court justice.First, a judge's life often is not very eventful - most particularly those years on the bench for which the subject is renowned. Deeds, triumphs, travel: These elements of the active life are not the claims on our attention made by a jurist's achievements. The work of mind and pen, important though it may be, is not inherently dramatic. Of course, some judges lead exciting careers before donning the robe. Chief Justice William Howard Taft was a former president, Chief Justice Earl Warren a former governor of California. Others, like Louis Brandeis, Felix Frankfurter, and Thurgood Marshall, were great lawyers before ascending to the bench. Not Holmes, who spent nearly 50 years as a judge - first in Boston, then three decades in Washington - before retiring in 1931 at age 90. Before that, his world was mostly law libraries. In speeches and writings, Holmes often extolled the bold spirit of the explorer, insisting that a man must "share the passion and action of his time"; but - except for his service in the Civil War - Holmes's own adventures and quests occurred mainly in his formidable intellect. A second, related difficulty for a judge's Boswell is that the biography essentially is legal history. The history of law is partly political and social history, but it's also the history of specialized ideas and concepts that, if the writer doesn't handle them adeptly, can be an impenetrable thicket for lay readers. But Baker, the author of two previous books on the Supreme Court, is up to the challenge of extracting from the details of Holmes's sedentary, cerebral life the striving, contradictions, and intellectual developments that command interest. Oliver Wendell Holmes Jr. was born in Boston in 1841, the son of a doctor and prominent man of letters. An offspring of the New England aristocracy, he never lost the genteel formality and class consciousness of his Brahmin upbringing. Intellectually, though, he was fiercely independent from his days as a Harvard undergraduate. In later years he retained his Beacon Hill manner, but Boston society looked askance at his "liberalism" and friendships with Jewish intellectuals such as Brandeis, Frankfurter, and Harold Laski. The Civil War was a seminal event in Holmes's life. He would later call the experience his "great good fortune," and his wife claimed that without it, Holmes would have been a "coxcomb." When the war broke out in 1861, Holmes left Harvard to join the Union army. During three years of relentless hardship and heavy fighting, the young officer took musket balls in his chest, neck, and heel. The war formed in Holmes a somewhat exaggerated creed of manliness, courage, and fortitude (akin to that of Theodore Roosevelt, the president who appointed Holmes to the Supreme Court in 1902, though Holmes, unlike the Rough Rider, was not a man for the outdoors). This creed complemented a philosophical view of life as a Darwinian struggle that was reflected in his jurisprudence. Throughout his life, Holmes larded his conversation and writing with military metaphors. Baker suggests that Holmes's later zeal for achievement - which took the form of a single-minded ambition that alienated some acquaintances - also may have derived partly from a need to justify his surviving a war in which so many comrades perished. After the war came Harvard Law School and a period of intense scholarship that culminated with the publication of his major work, "The Common Law," in time for his 40th birthday. Then in 1883 he took a seat on the Massachusetts Supreme Court. The rest of Holmes's career boils down to cases - to decisions, concurrences, and, not least in Holmes's case, dissents. But Baker's compelling narrative never bogs down. With economy she paints in the backgrounds of the important cases and traces the threads of Holmes's developing legal thought. Along the way, she deftly sketches his fellow judges and others in a circle that included William and Henry James, and she dips resourcefully into his correspondence and other contemporaneous sources to illumine his life on and off the bench. Holmes's judicial career coincided with a pivotal era in American history, when, in Baker's words, "19th-century laissez-faire had some of its most violent clashes with 20th-century tendencies toward collectivism." It was a time of rapid and unsettling economic and social change, and in case after case Holmes and his associates struggled to apply backward-looking legal principles to America's headlong rush into an urban and industrialized future. One of Holmes's chief claims to greatness, Baker shows, was the willingness of this upper-crust Yankee, this product of a Mayflower family line and Boston drawing rooms, to regard law as a growing, adapting organism that had to correspond to evolving modes of human life. More than with so many of his peers, Holmes's jurisprudence conscientiously contended against the ingrained habits and impulses of his ancestry and personal predilections. Baker is not uncritical of her subject. She acknowledges his aloofness and egoism, his intense ambition, and the hardness of his Malthusian pessimism and social Darwinism. She seems to prefer in a judge the passion of Holmes's early colleague John Marshall Harlan or his later colleague Brandeis to Holmes's own cool rationality. She observes that Holmes's reputation as a progressive was partly "unintentional," the result of a conservative judge's deference to the enactments of liberal legislators. And she suggests that the Holmes "legend" was in some measure the product of self-appointed promoters like Frankfurter and Laski. Yet Baker cannot help but admire - and cause us to admire - Holmes's personal and intellectual integrity, his commitment to duty and work, his devotion to justice, and a capacity for growth unwithered by age. This is a first-rate biography of a first-rate American.