Some good background, and a possible asnwer to the question you pose...
Not among the most stirring judicial defenses of the First Amendment you've ever heard. But it was enough to get the job done.
On June 30, 1971, the Supreme Court overturned the Nixon administration's effort to restrain The New York Times and The Washington Post from publishing a top-secret history of the Vietnam War called the Pentagon Papers.
Its unsigned opinion, in which six justices concurred, simply quoted from two other decisions ("Any system of prior restraints of expression comes to this court bearing a heavy presumption against its constitutional validity" ... the government "thus carries a heavy burden of showing justification for the imposition of such a restraint") before reaching this understated conclusion:
The District Court for the Southern District of New York, in The New York Times case, and the District Court for the District of Columbia and the Court of Appeals for the District of Columbia Circuit, in The Washington Post case, held that the government had not met that burden. We agree.
Joyful editors in New York ordered the immediate resumption of publication, which had been on pause since June 15, under court order. The Times had managed to print three installments of the series, which it called the "Vietnam Archive," before the government effectively shut it down, leaving much of the exposé unpublished....
I see similarities between the Pentagon Papers and the diplomatic cables, and the courage of Journalist Steven Edginton.