A US professor is trying to reclaim his personal data from the controversial analytics firm that helped Donald Trump to power. In what legal experts say may be a “watershed” case, a US citizen is using British laws to try to discover how he was profiled and potentially targeted by the Trump campaign.

David Carroll, an associate professor at Parsons School of Design in New York, has discovered a transatlantic legal mechanism that he hopes will give him access to information being sought by both the FBI and the Senate intelligence committee. In recent weeks, investigators looking at how people acting on behalf of Russia targeted American voters have focused on Trump’s data operation. But although the FBI obtained a court order against Facebook to make it disclose evidence, the exact way in which US citizens were profiled and targeted remains largely unknown.

But British data protection laws may provide some transparency on the company at the heart of Trump’s data operation – Cambridge Analytica – and how it created profiles of 240 million Americans. In January, Carroll discovered he – and a group of other citizens – had the right under UK law to ask for his personal data back from the company, and when it failed to supply it, he started filing pre-trial actions to sue the company under British law. The lawsuit is the result of a unique situation, according to Ravi Naik of Irvine Thanvi Natas, the British solicitor who is leading the case. It arose because although Cambridge Analytica is largely owned by Trump’s biggest donor, hedge-fund billionaire Robert Mercer, and though its vice-president at the time of the US election was Trump’s former chief strategist, Steve Bannon, the company was spun out of an older British military and elections contractor, SCL, with which it still shares staff, directors and a London office.

In the US, Americans have almost no rights over their data whatsoever Ravi Naik

Naik says: “It’s this fascinating situation because when it became apparent that Cambridge Analytica had processed Americans’ data in Britain, it suddenly opened up this window of opportunity. In the US, Americans have almost no rights over their data whatsoever, but the data protection framework is set up in such a way that it doesn’t matter where people are: it matters where the data is processed.

“I’m a human rights practitioner and in the past most of my cases were national security issues, but increasingly it’s about data protection and the way people are affected by the misuse of their data. I see this as an issue affecting fundamental rights and it’s taking citizen activism to uncover what’s going on, to request data. I really hear echoes of the civil rights movement in people becoming more aware, more resistant and willing to fight.”

As an academic, Carroll had studied advertising, data and design, but he was still shocked when Cambridge Analytica eventually sent him a “profile” that it had created about him though not the data it was created from. “It was very strange and unsettling because they had given me ‘scores’ for different issues but I had no idea what they’d based this on.” The company scored him 3/10 on “Gun Rights Importance”, 7/10 on “National Security Importance” and “unlikely” to vote Republican.

“I was perplexed by it. I started thinking, ‘Have I had conversations about gun rights on Facebook? Where are they getting this from? And what are they doing with it?’” He reported the firm to the UK Information Commissioner’s Office, which is investigating the use of data in political campaigning; he has also launched a CrowdJustice campaign and is appealing to the public to help him take the case as far as he can through the British courts.

It really is a David and Goliath fight and I think it will be the model for other citizens’ actions against other big corporations Frank Pasquale, University of Maryland

“There are so many disturbing aspects to this. One of the things that really troubles me is how the company can buy anonymous data completely legally from all these different sources, but as soon as it attaches it to voter files, you are re-identified. It means that every privacy policy we have ignored in our use of technology is a broken promise. It would be one thing if this information stayed in the US, if it was an American company and it only did voter data stuff.”

But, he argues, “it’s not just a US company and it’s not just a civilian company”. Instead, he says, it has ties with the military through SCL – “and it doesn’t just do voter targeting”. Carroll has provided information to the Senate intelligence committee and believes that the disclosures mandated by a British court could provide evidence helpful to investigators.

Frank Pasquale, a law professor at the University of Maryland, author of The Black Box Society and a leading expert on big data and the law, called the case a “watershed moment”.

“It really is a David and Goliath fight and I think it will be the model for other citizens’ actions against other big corporations. I think we will look back and see it as a really significant case in terms of the future of algorithmic accountability and data protection. These issues are so critical and in the US there are only these incredible, lethargic data laws largely because of the incredible power of the lobbying industry.”

Paul-Olivier Dehaye, a Swiss mathematician who has created the firm PersonalData.IO to help people reclaim their data, and who helped Carroll with his quest, said it was important that people realised that there are tools they can use against big corporations.

“In the US election, the FBI has been trying to get information from the top down but this doesn’t help with regard to the French election or Brexit,” Dehaye said. “And we know we just cannot trust Facebook, even with good intent, to run our elections fairly. There are a few huge companies amassing vast amounts of data on vast amounts of people and there’s no democratic oversight.”

Pasquale said news that Facebook information had been used by Russian agents to target US citizens may prove to be a tipping point. “It shows this information has now been weaponised by a state actor. What we’re seeing is really a failure of the first order. Mark Zuckerberg wrote this 6,000-word letter about creating a global political community and yet we now know that Facebook was a platform for a devastating attack on the most robust democracy in the world.”