Fifty years after four college students launched the sit-ins that eventually integrated department store lunch counters, the concept of segregation is almost incomprehensible to a large segment of the population.

That restrictive world forms the backdrop of Rawn James Jr.'s book chronicling the step-by-step dismantling of the laws that defined and maintained segregation.

Mr. James is specifically concerned with the court cases of NAACP lawyers Charles Hamilton Houston and his protege, Thurgood Marshall.

Mr. Houston and Mr. Marshall are the "root" and "branch" of the title; this book serves as a dual-biography of the two men with sidebar-like sketches of some of their associates.

Although Mr. Marshall's may be the more familiar name due to his role in Brown v. Board of Education and his Supreme Court tenure, the author says Mr. Houston taught Mr. Marshall all he knew of the law, "classroom to courtroom."

Mr. Houston grew up among the black middle class of Washington, D.C. After attending Amherst College, he studied law at Harvard, where he became the first African-American to serve on the Law Review and was mentored by future Supreme Court Justice Felix Frankfurter.

Mr. Houston was an officer during World War I and was then drafted by Howard University's president to overhaul its law school.

Working from the brief that their legal battles should be fought by "black attorneys with a blood-stake in their cases' outcomes," he set about transforming the program into a rigorous and respected law school for "social engineers."

He instilled into the students the belief that "African-American lawyers were obligated to know what the law should be. They had to know the Constitution better than the Supreme Court had allowed it to be known and trust its precepts more than the framers had themselves."

One of those students was Baltimore native Mr. Marshall. He'd applied to Howard only because the segregated University of Maryland would not admit him and he couldn't afford to attend a school farther north.

At Howard, Mr. Marshall began his lifelong association with Mr. Houston and in his third year, joined him in defending a black man accused of brutally murdering two white women in Leesburg, Va.

Mr. James opens "Root and Branch" with this case, diving right in without so much as an introduction. Drawing on his background as a lawyer, he presents concise, accessible accounts of legal strategy and courtroom proceedings.

(Elsewhere, unfortunately, he sometimes opts for overdone language, writing of a train that "rumbled like the world's largest empty stomach," for example.)

The trials covered are numerous, the victories large and small, the progress often slow. Even a successful outcome generally came too late for the actual plaintiffs.

They realized, as did their lawyers, that the benefits were for the future. The lawyers themselves struggled to balance professional and personal responsibilities all the while working in environments ranging from hostile to downright dangerous -- and degrading.

As Mr. James notes, at the height of his legal career, Mr. Houston "could not buy a lunchtime sandwich anywhere near his office in the [nation's] segregated capital."

Bit by bit, in courtrooms across the country, Mr. Houston, Mr. Marshall and their colleagues began to make a difference. Their legal successes gained African-Americans inclusion in jury pools, representation in trade unions and access to formally covenant-protected neighborhoods -- all crucial steps toward the ultimate goal of desegregating the nation's public schools.

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