It's been nearly five decades since former US Marine Corps officer Daniel Ellsberg leaked a US Department of Defence secret document, that came to be known as the Pentagon Papers, to a New York Times journalist.
With publication of the first articles, on June 13, 1971, the newspaper showed successive governments had lied to the American people about aspects of the Vietnam war and the degree of US involvement.
The US Department of Justice obtained a temporary restraining order that stopped the Times publishing after the third article.
In a famous Supreme Court case several weeks later the Times and the Washington Post joined forces to fight the US government and won, after the court ruled the government failed to prove publishing parts of the top secret report harmed national security.
The court found publication was justified under the first amendment to the American Constitution.
The Ellsberg case provided the foundation for the most famous media v government case of all, the Washington Post's investigation of the Watergate scandal that led to the resignation of President Richard Nixon.
Freedom of the press is a more precarious concept in Australia, as evidenced by Federal Police raids on the home of a News Corp journalist and ABC headquarters in Sydney.
The raids followed separate articles in 2017 about some government agencies proposing to extend their powers to monitor some Australians, and concerns about the conduct of Australian forces in Afghanistan.
The ABC raids were reportedly secured after a local court registrar signed a search warrant allowing Federal Police to access nearly 10,000 documents.
The raids were extensively reported by the ABC throughout the day.
And with every display of a document on a screen, with every sanctioned move by police throughout the ABC building, a message was being sent to the public about whistleblowing.
And the message was that people need to be afraid.
Most media outlets work extremely hard to strike that balance between reporting the truth that the public has the right to know about and protecting their sources.
Governments are responsible for national security and protecting citizens.
But history shows "national security" can become the blunt instrument governments use to avoid public scrutiny.