Why did some people clam that internment camps were unconstitutional?

As a result of the attack on Pearl Harbor in 1941 and until after the end of the war, the American government decided to confine hundreds of thousands of Japanese Americans who lived mainly on the west coast, fearing that they would collaborate with Japan during the war.

The confinement of Japanese Americans in internment camps was considered by many to be unconstitutional, illegitimate, arbitrary, and illegal. This is because the Constitution of the United States itself recognizes American citizens all civil rights, mainly freedom, without any distinction regarding race, ethnicity, color or national origin.