In Aptheker, the petitioner challenged Section 6 of the Subversive Activities Control Act of 1950, which made it a crime for any member of a Communist organization to attempt to use or obtain a passport.

[1] Appellants Herbert Aptheker and Elizabeth Gurley Flynn were native born citizens and residents of the United States and had held valid passports.

The three-judge District Court rejected appellants' contentions, sustained the constitutionality of § 6 of the Control Act, and granted the Secretary's motion for summary judgment, concluding that the enactment by Congress of § 6 was a valid exercise of the power of Congress to protect and preserve the Government against the threat posed by the world Communist movement and that the regulatory scheme bore a reasonable relation thereto.

In the US Supreme Court, appellants attacked § 6, both on its face and as applied, as an unconstitutional deprivation of the liberty guaranteed in the Bill of Rights.

As to the government's alternative theory, the clarity and preciseness of the provision in question made it impossible to narrow its indiscriminately cast and overly broad scope without substantial judicial rewriting which was beyond the power of the Court in this case.

The Court began with Kent v. Dulles,[2] reaffirming that the right to travel abroad was 'an important aspect of the citizen's 'liberty" guaranteed in the Due Process Clause of the Fifth Amendment.

But it concluded that the legislation was indiscriminate due to an absence of criteria linking the bare fact of membership in a Communist organization to the individual's knowledge, activity or commitment.

The Court then considered the government's alternate theory, rejecting it because the law was clear and precise and could not be judicially rewritten to take in only top party members.

And no authority to detain exists except under extreme conditions, e.g., unless he has been convicted of a crime or unless there is probable cause for issuing a warrant of arrest by standards of the Fourth Amendment."

"We cannot exercise and enjoy citizenship in world perspective without the right to travel abroad; and I see no constitutional way to curb it unless, as I said, there is the power to detain."