In Aptheker et al. v. Secretary of State, the U.S Supreme Court ruled that a section of the Subversive Activities Control Act (SACA) was unconstitutional because it violated Fifth Amendment rights to due process and First Amendment rights to freedom of speech and association. The SACA prohibited members of communist organizations from applying for or using passports, effectively restricting their international travel. Herbert Aptheker, a member of the Communist Party USA, challenged this law after his passport was revoked by the Department of State under its provisions. The court held in a 6-3 decision that while national security is important, it cannot be used as an excuse to infringe upon constitutional freedoms indiscriminately.

In the dissenting opinion for Aptheker et al. v. Secretary of State, Justice Clark argued that the majority's decision to strike down a law barring members of Communist organizations from obtaining passports was misguided. He contended that Congress had sufficient reason to believe that such individuals could pose a threat to national security and thus had acted within its constitutional authority in passing the legislation. Furthermore, he disagreed with the majority's assertion that this law violated First Amendment rights, arguing instead it was an appropriate measure taken by Congress in response to perceived threats during a time of heightened international tension and conflict (the Cold War). In his view, restricting passport privileges did not infringe upon these individuals' freedom of speech or association but rather served as necessary precautionary measures given their affiliation with an organization known for advocating overthrowing governments.