The Court of Appeal in the United Kingdom dismissed David Miranda’s appeal against Metropolitan Police for detaining him at Heathrow Airport for nine hours under the country’s terrorism law. But the court ruled the terrorism law violates the European Convention on Human Rights because it does not have “sufficient legal safeguards” to protect “journalistic information.”

Miranda, who is the spouse of journalist Glenn Greenwald, was assisting with reporting on documents from NSA whistleblower Edward Snowden. He was detained on August 18, 2013, en route from Berlin to Rio de Janeiro. Authorities detained him for the maximum period one can be held without charge under the law. The authorities also seized electronics equipment including a mobile phone, laptop, camera, memory sticks, DVDs, and gaming consoles.

The Security Services and Metropolitan Police targeted Miranda because they knew he had been staying with journalist Laura Poitras in Berlin. It was their objective to obtain access to documents from Snowden, which they suspected he was carrying.

In February 2014, the British High Court ruled the security services were well within their authority to take action so the “stolen” material did not become public for consumption and use by terrorists. The High Court adopted a very broad understanding of terrorism—that because the disclosure of documents from Snowden were deemed to be part of promoting a “political or ideological cause” then the disclosure fell within the definition of terrorism.

Now, the Court of Appeal has ruled [PDF] the terrorism law has two “fundamental defects.” There is no requirement “an examining officer” takes “into account the right to freedom of expression. “In particular, the risk that the examination of an individual, or the seizure, examination, retention, and/or copying of documents or data may intrude upon confidential journalistic material” is not part of any consideration. The potential disclosure of a confidential source is not considered either.

“This renders the circumstances in which the power can be used in relation to journalistic material unforeseeable and/or so broad as to require the strongest possible independent safeguards,” according to the decision.

When “journalistic material” is implicated or involved, there is no provision for obtaining authorization from a court or independent decision-making body to legally obtain access to the material. And, if there is an urgent risk claimed by authorities, the terrorism law does not outline any “bar on the inspection of such documents pending independent authorization.”

Article 10 in the European Convention on Human Rights declares, “Everyone has the right to freedom of expression. This right shall include freedom to hold opinions and to receive and impart information and ideas without interference by public authority and regardless of frontiers.”

“The central concern is that disclosure of journalistic material (whether or not it involves the identification of a journalist’s source) undermines the confidentiality that is inherent in such material and which is necessary to avoid the chilling effect of disclosure and to protect article 10 rights [under the Convention],” Lord Justice Stephen Richards wrote in the opinion.

“If journalists and their sources can have no expectation of confidentiality, they may decide against providing information on sensitive matters of public interest,” Richards contended. “That is why the confidentiality of such information is so important. It is, therefore, of little or no relevance that the [terrorism law] powers may only be exercised in a confined geographical area or that a person may not be detained for longer than nine hours.”

Richards noted the authorities judged Miranda to be carrying “journalistic material.” They knew he was helping Greenwald. There was no justification for disregarding this knowledge. The police should have conducted their stop with the frame of mind that whatever they sought was “journalistic material,” and they had an obligation to be aware of any rights implicated by their efforts to access the information.

Miranda was “thrilled with the court ruling.” He added, “My purpose was to show UK’s terrorism law violates press freedoms. And journalism isn’t ‘terrorism.’ We won!” Greenwald called it a “huge win.”

The British civil liberties organization, Liberty, hailed the decision as a victory. Rosie Brighouse, legal officer for Liberty, stated, “This judgment is a major victory for the free press.” She called the part of the terrorism law Miranda had challenged “a blot on our legal landscape for years—breathtakingly broad and intrusive, ripe for discrimination, routinely misused.”

“Its repeal is long overdue,” Brighouse added. “[The decision] is also a timely reminder of how crucial the Human Rights Act is for protecting journalists’ rights. Once again it has come to the rescue of press freedom in the face of arbitrary abuse of power by the State.”

Senior legal counsel David Banisar of Article 19, a British charity dedicated to freedom of expression, which supported the appeal, reacted, “When any overly broad security legislation is arbitrary applied and poorly regulated, there is a huge risk that important stories won’t be published and the press stifled.”

“With the Investigatory Powers Bill now going through the parliamentary scrutiny process, on a rushed timetable, this judgement serves as an argument for even greater scrutiny and a thorough review of powers which could have dramatic implications for freedom of expression in the U.K,” Banisar added.

The detention of Miranda at Heathrow Airport was one of the clearest examples of the lengths the British government would go to police and even censor journalism in order to obstruct reporting, which challenged security operations and government policies—including how mass surveillance impacted journalists.

British spy agents from GCHQ oversaw the destruction of hard drives The Guardian used to publish stories on documents from Snowden. As the World Association of Newspapers and News Publishers (WAN-IFRA) highlighted in its 2014 report on U.K. press freedom, “The newspaper [was] accused of ‘aiding Britain’s enemies’ by revealing the apparatus of state security and was told enough debate had been heard.” Prime Minister David Cameron claimed, while speaking before a parliamentary committee, that The Guardian had damaged national security. Then-editor-in-chief, Alan Rusbridger was summoned by a parliamentary inquiry and asked if he and his media organization “love this country.”

“These are actions more commonly seen in authoritarian regimes, where telling the press what to do is a regular part of government business,” WAN-IFRA declared.

It is now up to British parliament to determine what safeguard to add to the terrorism law so press freedom is adequately protected.