So the worst decisions in its history are probably something like:
-
Dred Scott v. Sandford (1857): Black Americans, free or enslaved, could not be U.S. citizens, and Congress had no power to ban slavery in the territories.
-
Plessy v. Ferguson (1896): Upheld racial segregation under the “separate but equal” doctrine AKA Jim Crow laws
-
Korematsu v. United States (1944): Upheld the internment of Japanese Americans during WWII as a wartime necessity.
-
Citizens United v. FEC (2010): Corporations and unions can spend unlimited money on independent political advertising, citing free speech.
For third worst I think I’d have to pick Korematsu