What is the name to identify an irrational fear of foreigners?

In the supreme court’s decision in korematsu v. united states, the court said that korematsu

Which statement about submarine use in world war i is true? the allies never found a way to counter german submarine warfare. germany’s use of submarines affected the united states’ decision to enter the war. only the germans used submarines in world war i.

The supreme court settle conflicts between the various levels of government true or false ?