The First Amendment to the U.S. Constitution, which guarantees the freedom of speech and the press, only means that "every man shall be at liberty to publish what is true, with good motives and for justifiable ends.” So wrote the Supreme Court justice Joseph Story, who argued that without such a limitation, the amendment could become "the scourge of the republic by rendering the most virtuous patriots odious through the terrors of the press, introducing despotism in its worst form.”

The interpretation of Story, who died in 1845, framed American understanding of the freedom of the press for most of the nation’s history. It stayed in place until 1931, when the passages above were cited by the four justices who dissented in the case of Near vs. Minnesota, which established that prior restraints on the press were unconstitutional. Press freedom as currently understood in the U.S. dates back only 94 years.

It’s important to bear this in mind after the announcement by the Pentagon in a 17-page memo that journalists will now be required to undertake only to publish material that has been "approved for public release by an appropriate authorizing official, even if it is unclassified.” If they don’t sign this undertaking, they lose their access to the building and all military facilities, and with it, their ability to cover the defense policy of the world’s largest military power.