David Miranda, the partner of Guardian journalist Glenn Greenwald, was detained this weekend for nine hours at London's Heathrow Airport. He was held without access to a lawyer and questioned under a British anti-terrorism law. When he was finally released, British authorities confiscated his laptop, cellphone and other electronic devices.

Greenwald, of course, is the journalist who first reported on whistleblower Edward Snowden's leaked documents, which reveal widespread, unchecked surveillance programs in the United States and England.

Police in the U.K. have refused to discuss why Miranda was detained, but he was traveling from Berlin, where he visited documentary filmmaker Laura Poitras, who has been working with Greenwald on the Snowden leaks. Greenwald said that Miranda was carrying encrypted files between to and from Poitras as part of their ongoing reporting.

Intimidating journalists and harassing their family members are tactics used by totalitarian regimes, not democratic governments. The detainment of Miranda was an outrageous attack on press freedom designed to send a message to Greenwald, Poitras and other journalists covering national security.

In response, Free Press is launching a campaign calling on the U.S. and U.K. government's to halt the intimidation of journalists and their families. Join the effort here. 

Poitras is an award-winning filmmaker, but because she covers war and security issues, U.S. border agents have detained and questioned her more than 40 times. “It’s an intimidating situation,” Poitras recently told the New York Times, “when people with guns meet you when you get off an airplane.”

While the White House has said it had no role in Miranda’s detention, its own track record is hardly stellar.

Earlier this year, the Justice Department was caught spying on Associated Press journalists, and went so far as to label a Fox News journalist a “co-conspirator” in a leak investigation. Right now, the Department is trying to force a New York Times reporter to reveal the source of another leak — and threatening him with jail time if he doesn’t comply. And journalists who try to cover trials — like that of Bradley Manning — have to do so with armed military policy looking over their shoulders.

We’re seeing an unprecedented rise in attacks and intimidation directed at the press. These journalists need our help.

This behavior won’t stop unless the public raises its voice. In the end this isn’t about individual journalists or any specific case. It's about everyone’s rights to share information, make media and hold our leaders accountable. It's about journalists' role in exposing information our leaders would rather keep hidden.

Journalists like Greenwald and Poitras — and their families, their colleagues and anyone committed to serious in-depth reporting — need our help now. The first step is to speak out, but we can’t stop there.

UPDATE: The editor of the Guardian has posted a long and revealing description of how U.K. authorities pressured him to destroy documents related to the Edward Snowden leaks, and eventually came to the Guardian's London headquarters and oversaw the destruction of hard drives and computers.