Forty years ago, a contentious battle over racial justice gripped Capitol Hill, pitting the nation’s lone African-American senator against the man who would one day become Barack Obama’s vice president. The issue was school busing, a plan to transport white and black students out of their neighborhoods to better integrate schools—and at the time the most explosive issue on the national agenda.

Ed Brooke, a Massachusetts Republican, was the first black senator ever to be popularly elected; Joe Biden was a freshman Democratic senator from Delaware. By 1975, both had compiled liberal voting records. But that year, Biden sided with conservatives and sponsored a major anti-busing amendment. The fierce debate that followed not only fractured the Senate’s bloc of liberals, it also signified a more wide-ranging political phenomenon: As white voters around the country—especially in the North—objected to sweeping desegregation plans then coming into practice, liberal leaders retreated from robust integration policies.  

Biden was at the forefront of this retreat: He had expressed support for integration and—more specifically—busing during his Senate campaign in 1972, but once elected, he discovered just how bitterly his white constituents opposed the method. In 1973 and 1974, Biden began voting for many of the Senate’s anti-busing bills, claiming that he favored school desegregation, but just objected to “forced busing.”

Then, as a court-ordered integration plan loomed over Wilmington, Delaware, in 1974, Biden’s constituents transformed their resistance to busing into an organized—and angry—opposition. So Biden transformed, too. That year, Joe Biden morphed into a leading anti-busing crusader—all the while continuing to insist that he supported the goal of school desegregation, he only opposed busing as the means to achieve that end.

This stance, which many of Biden’s liberal and moderate colleagues also held, was clever but disingenuous. It enabled Biden to choose votes over principles, while acting as if he was not doing so. ...