"Plessy" legitimized state laws establishing racial segregation in the South and provided an impetus for further segregation laws. It also legitimized laws in the North requiring racial segregation such as in the Boston school segregation case noted by Justice Brown in his majority opinion. Legislative achievements won during the Reconstruction Era were erased through means of the "separate but equal" doctrine. The doctrine had been strengthened also by an 1875 Supreme Court decision that limited the federal government's ability to intervene in state affairs, guaranteeing to Congress only the power "to restrain states from acts of racial discrimination and segregation". The ruling basically granted states legislative immunity when dealing with questions of race, guaranteeing the states' right to implement racially separate institutions, requiring them only to be "equal".