On what constitutional basis did the supreme court deny korematsu’s appeal?

The Supreme Court ruled that Executive Order 9066 was indeed constitutional. This order resulted in the removal of Japanese-American citizens, regardless of their citizenship status, into internment camps.  Korematsu, a Japanese-American citizen, sued the government for this mistreatment and charged them with violating the constitution.

However, the court ruled in favor of the government. The reason why they did was because they felt that the need to protect American society from Japanese spies outweighed the rights of Japanese-American citizens.