three races, africans and mongol oids as they are called as and caucasian as whites were called. there is this pseudo racial science which tries to give a supposedly objective grounding to what is ultimately a system of prejudice. >> the case of plessy versus ferguson in 1996 show how ash traesh dechgss ofs race can be in america. >> a man white by any definition, whommer plessy but considered black because one black ancestor. >> plessy intentionally boarded a whites only train car in louisiana. challenging the separate but equal laws. >> the conductor came and said get out of this car. you're not white. >> when plessy refused to leave he was arrested. in what became known as the separate but equal decision, the sprurt ruled against plessy