In an outrageous and unacceptable attack on press freedom, Guardian journalist Glenn Greenwald’s partner, David Miranda, was detained for almost nine hours at Heathrow airport in London earlier today under section 7 of the UK’s pernicious Terrorism Act. Miranda was returning to his home in Brazil after a week-long visit with documentarian Laura Poitras. Miranda, whose flights were paid for by the Guardian, was reportedly bringing important documents back to Greenwald on USB thumbdrives.

Greenwald and Poitras (both of whom are on our board of directors) have been the central journalists reporting the recent stories on the NSA, based on leaked documents provided to them by whistleblower Edward Snowden. Miranda was detained for eight hours and fifty-five minutes by security, for much of it he was denied access to a lawyer, while being asked questions about the NSA. His electronics, including his phone, computers, and USB thumbdrives, were confiscated and not returned when he was released.

It is unclear what the UK government was trying to accomplish by detaining Miranda. Likely, it was meant as some form of intimidation. But surely, it will backfire. Investigating acts of journalism under “terrorism” laws and detaining family members of reporters are hallmarks of authoritarian regimes.

Regardless of whether this was an aberration or somehow a horrible mistake, it sends exactly the wrong example to countries the US and UK regularly excoriate for human rights abuses. Take, for example, this report from Human Rights Watch from a year ago: “The Iranian government has been intimidating and detaining relatives and friends of foreign-based Persian-language journalists to obtain information or silence them.”

And until UK government takes swift action to rectify this injustice, other journalists — and their loved ones — should be on alert. Not only was Miranda detained, but Greenwald's journalistic work-product was seized. As Andrew Sullivan wrote, “So any journalist passing through London’s Heathrow has now been warned: do not take any documents with you. Britain is now a police state when it comes to journalists, just like Russia is.”

The most appalling part of the story is the use of UK’s “terrorism” law as a guise to detain David, who, of course, has nothing to do with terrorism. Just like the Patriot Act and FISA Amendments Act, which have been used by the NSA to create mass domestic surveillance databases of millions of innocent people, the “terrorism” law in the UK declares the “power to stop and question may be exercised without suspicion of involvement in terrorism.”

The NSA stories published by Greenwald and others have prompted an unprecedented debate in the US about the government’s vast surveillance powers, and major reforms now seem likely to pass Congress. Maybe this incident will spark renewed outrage over Britain “terrorism” law, which thousands of innocent people have been subject to, and laws permitting suspicion-less border searches in general.

Ironically, this incident comes the same day as a long profile in New York Times Magazine of Poitras, who has shamefully been the subject of similar harassment at the border by the US for years, solely because she produces journalism that the United States government apparently does not like. It’s unknown whether the US had any involvement in the detention of Miranda but questions should be asked as to what they knew and when.

In the meantime, the UK government owes Mr. Miranda a prompt apology, return of the property they stole from him, and assurances it won’t happen again.