As America moved to integrate its schools in the mid-1900s, Boston, like many Northern cities, struggled with segregated housing patterns. Because students were assigned to schools based on where they lived, schools in primarily white areas such as South Boston and Charlestown had a mostly white student body, while schools in black areas such as Roxbury were overwhelmingly black. The earliest Supreme Court school desegregation decisions, however, outlawed only the de jure segregation prevalent in Southern schools, where laws specifically forbade blacks and whites from attending school together. The decisions did not condemn de facto segregation such as that in Boston. Indeed, in the Supreme Court's unanimous majority opinion in Brown v. Board of Education, Chief Justice Earl Warren stated, "Segregation in Boston public schools was eliminated in 1855." 
In the early 1970s, the Supreme Court began to turn its attention from schools in the South to those in the North. The justices soon discovered that achieving desegregation in these schools would require different tactics. In the South, blacks and whites had lived in close proximity to each other for hundreds of years; therefore, desegregation was simply a matter of assigning students to the school closest to their home. This strategy did not work in the North because of segregated housing patterns. So in Swann v. Charlotte-Mecklenburg (1971), the Court approved the utilization of measures that were "administratively awkward, inconvenient, and even bizarre" to achieve integration.  Busing was among the measures specifically approved by Swann.
A year after Swann, Morgan v. Hennigan was filed in the U.S. District Court for the District of Massachusetts, charging that Boston's public schools were unconstitutionally segregated. In a similar 1964 case, the Court of Appeals had ruled that de facto segregation was not unconstitutional. To avoid the same decision in Morgan, prosecuting attorney Nick Flannery worked to prove that Boston's segregation was not de facto but actually de jure, just like the segregation in the Southern school districts that the Supreme Court had worked for nearly two decades to eradicate. "Fortunately, the Boston School Committee had . . . [kept] verbatim stenographic accounts of its meetings, providing a clear record of resistance to desegregation, as well as hints of its motivations."  The strategy worked. On June 21, 1974, Judge W. Arthur Garrity "found that the School Committee had used covert techniques to segregate the system, and had done so with 'segregative intent.'"  Garrity's decision was upheld on appeal, and the judge set about working on a remedy for the segregation he had found. With only three months left before the 1974-1975 school year opened, he was forced to adopt an existing plan as his first-stage remedy (Phase I) for that school year while he worked on his own more permanent plan (Phase II).