“Citizenfour” is a documentary about NSA whistleblower Edward Snowden. It came out in 2014, but it’s even more pertinent today than it was then, so if you haven’t seen it, I urge you to do so. The Snowden story began in January 2013, when documentary film director/producer Laura Poitras received an encrypted email from a stranger who called himself “Citizen Four.”

Poitras had already spent several years working on a film about monitoring programmes in the US and had been placed on a secret watch list after her 2006 film My Country, My Country, a documentary about Iraqis living under US occupation.

“Laura. At this stage, I can offer nothing more than my word. I’m a senior government employee in the intelligence community. I hope you understand that contacting you is extremely high risk and you’re willing to agree to the following precautions before I share more. This will not be a waste of your time …

“The surveillance you’ve experienced means you’ve been ‘selected’ – a term which will mean more to you as you learn about how the modern SIGINT [signals intelligence] system works.

“For now, know that every border you cross, every purchase you make, every call you dial, every cell phone tower you pass, friend you keep, article you write, site you visit, subject line you type, and packet your route, is in the hands of a system whose reach is unlimited, but whose safeguards are not.

“Your victimisation by the NSA system means that you’re well aware of the threat that unrestricted secret police pose for democracies. This is a story few but you can tell.”

In June 2013, Poitras flew to meet Snowden at The Mira Hong Kong, together with columnist Glenn Greenwald and Ewen MacAskill, an intelligence reporter for The Guardian. After four days of interviews, Snowden’s identity was made public at his request.

Within two weeks, the US government demanded Snowden’s extradition. Facing prosecution in the US, Snowden scheduled a meeting with the United Nations High Commissioner for Refugees and applied for refugee status.

He managed to depart Hong Kong but became stranded at the Sheremetyevo International Airport in Moscow when his passport was cancelled. There he remained for 40 days until the Russian government finally granted him asylum.

The US government implemented Stellar Wind, a programme to actively – and illegally – spy on all Americans within days of the 2001 9/11 attack. Ten years later, in 2011, construction began on an NSA data centre in the Utah desert. It’s now the largest surveillance storehouse in the US.

In his correspondence, Snowden warned Poitras that “telecommunication companies in the US are betraying the trust of their customers.” Through Stellar Wind, all phone calls and text messages were being intercepted and stored, and the Stellar Wind programme has only expanded from there.

The NSA not only intercepts American citizens’ emails, phone conversations and text messages but also Google searches, Amazon.com orders, bank records and more.

“We are building the greatest weapon for oppression in the history of man,” Snowden wrote, “yet its directors exempt themselves from accountability. On cyber operations, the government’s public position is that we still lack a policy framework. This … was a lie. There is a detailed policy framework, a kind of martial law for cyber operations created by the White House. It’s called ‘Presidential Policy Directive 20’ and was finalised at the end of last year.”

As explained in the film, a key aspect of control through surveillance is the linkability of data. One piece of data about you is linked to another piece. For example, your bus pass can be linked to the debit card you used to buy the pass. Your debit card is also linked to all other purchases.

With two key pieces of information – WHERE you went on a given day, and WHEN you made purchases, they can determine who you spoke with and met up with by linking those data points with those of other people who were in the vicinity at the same time.

And that’s without even using your cellphone data.

When all these various data points are aggregated – location data, purchases, phone calls, texts, social media posts and more – you end up with a collection of metadata that tells a story about you. However, while the story is made up of facts, it’s not necessarily true.

For example, just because you were standing at a particular street corner does not mean you had anything to do with the crime that was reported on that same corner at the time you happened to be there. The problem is that your data could be used against you in that way.

The January 6 prisoners are a perfect example of how bits and pieces of data can be misused. Many have now spent years in jail simply because their cellphone data showed them as being in the wrong place at the wrong time.

When asked by Greenwald why he decided to become a whistleblower, Snowden replied: “It all comes down to state power against the people’s ability to meaningfully oppose that power. I’m sitting there every day, getting paid to design methods to amplify that state power. And I’m realising that if the policy switches that are the only thing that restrain these states were changed, you couldn’t meaningfully oppose [them].

“I mean, you would have to be the most incredibly sophisticated tactical actor in existence. I’m not sure there’s anybody, no matter how gifted you are, who could oppose all of the offices and all the bright people, even all the mediocre people out there with all of their tools and all their capabilities.

“And as I saw the promise of the Obama administration be betrayed … and in fact, [how they] actually advanced the things that had been promised to be sort of curtailed and reined in and dialled back … As I saw that, that really hardened me to action. …

“We all have a stake in this. This is our country, and the balance of power between the citizenry and the government is becoming that of the ruling and the ruled, as opposed to the elected and the electorate.”

“I remember what the internet was like before it was being watched, and there’s never been anything in the history of man like it,” Snowden said.

“You could have children from one part of the world having an equal discussion, where they were sort of granted the same respect for their ideas and conversation, with experts in a field from another part of the world on any topic, anywhere, anytime, all the time.

“It was free and unrestrained. And we’ve seen the chilling of that, and the changing of that model towards something in which people self-police their own views. They literally make jokes about ending up on ‘the list’ if they donate to a political cause, or if they say something in a discussion. It’s become an expectation that we’re being watched.

“Many people I’ve talked to have mentioned that they’re careful about what they type into search engines because they know that it’s being recorded, and that limits the boundaries of their intellectual exploration.”

Today, after the extreme ramp-up of censorship, surveillance and harassment we’ve endured since the Covid-19 pandemic began, Snowden’s warnings ring truer than ever.

Artificial intelligence now scours social media, podcasts and videos for keywords identifying “anti-vaxxers,” for example.

It doesn’t even matter if they agree with what you’re writing or saying. The mere inclusion of certain words will get you axed from the platform. Snowden’s worst fears have indeed come true, and today most people have come to realize just how dangerous this kind of blanket surveillance can be.

• The Defender report / By Dr Joseph Mercola