In 1883, several civil rights cases came before the supreme court that were related to
a) freedom of speech and the ku klux klan.
b) land ownership for southern sharecroppers.
c) discrimination in public facilities.
d) voting, poll taxes, and literacy tests.

so they can differentiate themselves from others as they saw themselves as the superior race. the star was basically a symbol that meant you are a less of a person than i am because of my race. the star was also degrading for those who had to wear it because they were aware of this and the nazis used the notion to make them feel less like a person.