sentences:  Finally, the Court held that the Government was not required to hold a pre-revocation hearing, since where there was a substantial likelihood of "serious damage" to national security or foreign policy as the result of a passport holder's activities abroad, the Government may take action to ensure that the holder may not exploit the United States' sponsorship of his travels.Further, a statement of reasons and an opportunity for a prompt post-revocation hearing were sufficient to satisfy the Constitution's due process guarantees.Blackmun concurred, stating simply that he believed this case had cut back somewhat on the standards articulated in "Zemel v. Rusk" and "Kent v. Dulles" "sub silencio" and that it would have been better if the Court had forthrightly construed the law such that evidence of a longstanding Executive policy or construction in this area be probative of the issue of congressional authorization.