A German police helicopter swoops in low over the United States' consulate in Frankfurt, hovers and then departs. Photos of antennae on the roof of the building have been taken. Mission accomplished. This scene, reminiscent of a bad cold war movie, is the German government's most visible action in response to the whistleblower Edward Snowden's revelations that America is spying on the world and has, among other things, "eavesdropping posts" at 80 US embassies and consulates around the world.

If the internet is a global highway, one of its busiest junctions, called DE-CIX, is buried deep under Frankfurt. We don't require specifics from Snowden to know that US spy agencies must be monitoring this. They have taken Obama's "Yes we can" to a sinister new level. In this context, photographing rooftop antennae is almost laughable.

There have been voices calling for a more robust reaction from the German government, and a number of protest marches by citizens. Nevertheless many, even critical Germans, are resigned to saying in the face of the NSA scandal: "We all know everyone is watching everyone all the time anyway. That's just the way it is."

How can we just shrug at the fact that our private lives are subject to unsanctioned state surveillance? We are in danger of forgetting that there is a crucial distinction between us choosing to have some personal data in a space where it might be accessible to strangers, and all our personal data being available for foreign spy agencies to view without permission, and without us having a clue. Article 10 of the German constitution enshrines the right of citizens to privacy – no surveillance of an individual is possible without court approval. This emphasises that only those who may be guilty should be watched.

We cannot be complacent about how this basic law is being undermined by the NSA. In an open letter to Angela Merkel published in July, the novelist Juli Zeh described it as "a historic attack … on the innocent until proven guilty principle". Zeh also highlighted Merkel's unsatisfactory response to the issue and since then the chancellor has simply continued with hinhaltetaktik (delaying tactics), even peddling a weak argument that many emails sent within Germany go via a server in the US and may therefore be outside the jurisdiction of German law. The cause of Merkel's evasiveness is obvious – she's hoping to sit out the issue until after the election. Which begs the question – what is she afraid of?

Whatever she might be reluctant to reveal, however she dissembles, we will not stop probing. It is in this indignant, challenging spirit that Zeh and around two dozen authors plan a march to the chancellor's residence on Wednesday to hand over the signatures of the 65,000 German citizens who have signed the open letter (now a petition at Change.org).

Throughout history, writers have resisted oppression, lies and censorship with their work. Sometimes, they have to step outside their writing to declaim injustice publicly on behalf of the people. And, occasionally, the threat to freedom is so immense that writers band together in their outrage. It happened in Germany in 1947, when leading German writers including Heinrich Böll, Günter Grass and Paul Celan formed Group 47 with a view to upholding democracy and ensuring accountability in the aftermath of the Nazi era.

The writers who will march on the chancellery on 18 September do so with an awareness of their illustrious predecessors, and the knowledge that it has been a while since writers took such a public stand together.

Data is probably the most precious resource we have in Europe – the only commodity we can hope to mine endlessly is our brain. We depend on our thoughts, our ideas, our innovations, and if we can't protect this domain, we risk losing copyright over our own identity – and therefore over our inventions and over our future. Moreover, our very ability to create will be undermined by the fact that we can't do so freely – because being free means not being watched.

As a British citizen who spends a lot of time in Berlin, I'm relying on Germany to take a strong moral stand on the NSA issue in the hope that this will help steer the rest of Europe in a backlash against such indiscriminate, blanket surveillance of citizens. Germany needs to tell America: no you can't.