As the focus shifts from whistleblower Edward Snowden’s travel itinerary to the fallout from his dramatic revelations of widespread NSA surveillance, the United States and United Kingdom governments have been trying to justify widespread spying on their own citizens by pointing to the general threat of terrorism. But with the partner of The Guardian journalist who broke the story detained at an airport, these justifications are beginning to look thin.

On Sunday, David Miranda was arrested and detained for almost nine hours by security officials at Heathrow Airport under schedule seven of Britain’s Terrorism Act. Schedule seven allows an examining officer to detain and question someone at a port of entry to determine whether that person is preparing, instigating or commissioning terrorism. Miranda is Brazil-based Guardian journalist Glen Greenwald’s partner and assistant. More recently he wrote several articles about the UK’s complicity in NSA spying initiatives, how UK intelligence spied on at least British allies at two London summits, and on US funding of the UK’s GCHQ eavesdropping operations.

Miranda was en route to Brazil from Berlin, where he met with Laura Poitras, a US filmmaker working with Greenwald and The Guardian on NSA-related matters. According to Miranda, security services officers confiscated his laptop and other electronic devices, threatening with prison if he refused to disclose passwords.

His detention in terms of the Terrorism Act sends a powerful message to anyone who crosses the surveillance state — as does WikiLeaks whistleblower Chelsea (Bradley) Manning’s sentence of 35 years in a military prison. Both show the commitment of security establishment in the UK and the US to maintain their surveillance fiefdom as it is. The UK police seem to have deliberately avoided invoking normal statutory procedures in the UK’s Police and Criminal Evidence Act to request permission to search and obtain confidential journalistic material. Lord Charles Falconer of Thornton, a former Labour lord chancellor who in 2003 helped to introduce the anti-terror laws used to detain Miranda, told The Guardian: “I am very clear that this [the Terrorism Act] does not apply, either on its terms or in its spirit, to Mr Miranda.”

The fact that the security services are generally well resourced to counter terrorism is reassuring. The fact that security services have advanced surveillance capabilities to counter terrorism was known before Snowden’s disclosures and is widely accepted. However, the wider purposes to which surveillance programs have been put, and the continuing secrecy and demonstrable lack of oversight around these programs, have sent a chilling message to journalists reporting on Snowden’s disclosures, and to the public. More so when draconian anti-terrorism laws that potentially grant wide powers to security officials are used for unintended purposes.

“Oversight and accountability disciplines and focuses the use of coercive powers by the state, a valuable lesson history has taught us.”

Miranda is not alone. According to the UK’s independent reviewer of terrorism legislation, David Anderson QC, 61,145 people were detained and questioned at airports and ports in the UK during the past year in terms of schedule seven of the Terrorism Act — only 24 arrests followed. That’s an efficiency rate of around 0.03% as far as schedule seven is concerned. In terms of similar Australian federal laws, section 34 of the ASIO Act, an ASIO officer may in limited circumstances detain and question a person in order to gather information for preventing terrorist attacks. A person may be detained for up to seven days, but any coercive questioning or detention must be authorised by a warrant obtained from a federal judge or federal magistrate, and a detainee has a range of procedural rights. This power is seldom used — it has not been used once in the past three years.

Oversight and accountability disciplines and focuses the use of coercive powers by the state, a valuable lesson history has taught us. The fallout from the Snowden disclosures, and their consequences, have called into stark focus the tension that exists between the right to privacy, freedom of the press, and the legitimate demands of national security. It is at this intersection of competing rights and demands that government-led oversight, accountability and integrity are most in demand. Anything less will turn out to be illusory, leading to unanticipated and unintended consequences.

The NSA relies on the co-operation, mostly involuntary, of US-based communications and technology companies to provide them with data. A company has two choices: resist, and risk its leaders being jailed, or comply and sacrifice customers’ privacy. Two weeks ago, two US-based secure email service providers chose a third option. Dallas-based Lavabit implied that it had received a demand for surveillance data of its customers, as recipients of secretly issued government surveillance orders are usually prohibited from disclosing or discussing them publicly. Owner Ladar Levison announced in a letter to customers that after 10 years of hard work he would be shutting down Lavabit. Shortly afterwards, Silent Circle, which operates an encrypted email service Silent Mail, cited the Lavabit decision and announced that it was pre-emptively shutting down Silent Mail.

Society, technology companies and the internet will no doubt evolve and adapt to wherever the area of tension between privacy and national security settles at over time. Governments, and society, have the opportunity now to transparently chart where this area of tension should be, to shape a known area rather than one that is unknown. It is a global issue, and an Australian issue. Pity it’s not an election issue, as that is where it belongs. In the meantime, unintended and unpredictable events may well be the order of the day. Ask Miranda, Lavabit and Silent Circle, to name but a few.