The United States Supreme Court case, United States ex rel. Knauff v. Shaughnessy, dealt with the issue of immigration and executive power. Ellen Knauff, a German woman married to an American citizen and war veteran was denied entry into the U.S based on confidential information that she posed a security risk. The decision to exclude her was made by the Attorney General under an Executive Order issued by President Truman in 1945 granting him broad powers over alien enemies' entry during times of war or national emergency without providing reasons for exclusion or allowing for judicial review. Knauff challenged this action as unconstitutional arguing it violated her due process rights because she wasn't given any hearing or reason for denial of admission into the country. However, in a 4-3 decision, the Supreme Court upheld her exclusion stating that matters concerning who can enter or stay in America are largely within Congress's discretion and can be delegated to executive officials like the Attorney General; therefore no hearing is required before excluding aliens seeking entrance at borders since such decisions fall under political questions rather than legal ones.

In the dissenting opinion for United States ex rel. Knauff v. Shaughnessy, Justice Jackson argued that the majority's decision was a departure from traditional American principles of justice and due process. He contended that it was unconstitutional to deny an individual entry into the country without providing them with a fair hearing or disclosing any specific charges against them. Furthermore, he criticized the use of executive power in this case as excessive and unchecked by judicial review, which could set a dangerous precedent for future cases involving immigration law and national security issues. In his view, such broad authority should not be vested solely in administrative officers without some form of legal oversight or protection for individuals' rights.