Dr Chelsea Polis is a reproductive health scientist based in New York City. She was sued for $1m by a medical device company after speaking out about misleading marketing claims it had made about the use of its digital fertility tracker as a contraceptive method. After a two-year battle, the case was thrown out of court. Last month in London she won the 2023 John Maddox prize early career award, which champions those who stand up for evidence-based science in the face of hostility. She is a senior scientist for epidemiology at the Population Council’s Center for Biomedical Research.

In May 2020, you were sued for $1m for defamation by Valley Electronics of Zurich, Switzerland, the manufacturer of the Daysy fertility tracker and the DaysyView app, for voicing your concerns about the device being marketed as a contraceptive. How did it feel as an individual to be sued for $1m?
Shocking. Terrifying. Completely bewildering because what I was being sued for was something where my concerns had been validated, not only by a scientific journal, but also by a US federal agency – the US Food and Drug Administration [FDA], which had taken my concerns seriously and launched an investigation, after which the company changed their marketing language.

What was the company claiming and what were your concerns?
Daysy is a fertility thermometer that tracks your menstrual cycle start date, and every day you use it to take your basal body temperature. What the thermometer then tries to do is estimate the days of your menstrual cycle when you’re most likely to be fertile. What I noticed back in 2017 was that the company was marketing it as a contraceptive method, with claims that it was as effective as an IUD [intrauterine device] – one of the most highly effective methods available. They were marketing it as being over 99% effective for contraceptive use, and that claim was based on a very flawed study and it was in violation of Food and Drug Administration regulations around the marketing of contraception.

What was the company’s evidence for marketing Daysy as a contraceptive method and how did you respond to that?
There were two main studies that it has referred to over time. One was published in 1998 on a predecessor device called Lady-Comp. That was the study that I originally saw when I directly reached out to the company to raise my concerns because I saw how it had actually incorrectly calculated contraceptive effectiveness. When I asked: “Have you ever done a study with prospective pregnancy measurement?”, which would be required to adequately assess the effectiveness of the device, it said: “Oh, we’d love to do such a study, but the costs and benefits are all out of proportion.” That was appalling to me because that is… so ignorant of the potential costs of an unintended pregnancy that might occur at greater-than-expected risk to somebody who believes that this device is 99% effective at preventing pregnancy.

Then, a couple of months later, a new study was published. My main issue with it was that the methods were a disaster in terms of the way it collected and analysed the data. I published a commentary in June 2018 in the same journal, Reproductive Health. It laid out all the flaws and called for the paper to be retracted. A year later, I found out that they [the journal] had obtained some independent expert and confirmed that my concerns were valid. The journal did retract the paper and also permitted the authors to write a response letter.

And you also got in touch with the regulator, the FDA, to ask it to investigate…
The very day my peer-reviewed commentary was published, I reached out to the FDA to submit an allegation of regulatory misconduct, which basically flags concerns [over potential marketing violations]. A lot of these claims were being published on social media, where you have an audience of disproportionately younger people, and younger people are at a disproportionately higher risk of unintended pregnancy. Everybody should have access to accurate information about their contraceptive options, but for young people in particular, it’s very troubling to see what I considered blatant misinformation being spread like wildfire, truly.

On what basis did the company sue you?
Obtaining a successful retraction of a scientific paper is not easy – it generated a fair amount of media interest, which I was very pleased about because the people most likely to be considering or already using Daysy are not going to be following the nuances of what happens in a scientific journal. So I did a number of media interviews, in some of which I used descriptors that the company claims were defamatory – and sued me for $1m.

In the end, Dori Hanswirth and her team at law firm Arnold & Porter offered you pro bono help – how did that come about?
I was unbelievably lucky. I summarised the situation for them, they were appalled and very generously spent the next two years and goodness knows how much [on my case]. I am a privileged white woman who lives in New York City and has lawyers in her family. This was the first time I’ve ever had any engagement with the legal system and by having connections – which not everybody has – I was put in touch with a family friend who knows about the different law firms and knows those that have large pro bono practices. She gave me a list of people that I should consider reaching out to and advised me to put together a document that laid out the details of my case.

And I emphasise my positionality in all of that because what this has taught me is that was the result of my privilege; of being connected to people like that, having the time and resources to put together a document in the midst of other things going on. If an earlier career person, or somebody in a less financially stable position, or with a less supportive family, or without those kinds of social connections, or a host of other things… if they didn’t have those comforts and privileges that I had, they would have had much less chance of getting the help that they would desperately need to be able to defend the truth.

What was the outcome of the case?
We won on a motion to dismiss it within a little over a year. We were very happy and then, not too long thereafter, we heard Valley Electronics had appealed to the second circuit court of appeals. So like, really? OK. Round two. It took a little bit less time this time for it to be thrown out again.

I understand you are now an active advocate of advancing federal anti-Slapp (strategic litigation against public participation) legislation in the US. Can you say a bit about that?
Slapp stands for strategic litigation against public participation. And these kinds of suits are often filed by powerful interests seeking to silence those speaking up about concerns that are generally a matter of public interest. They happen everywhere, but they work differently everywhere. In the US, depending on where you live, you may have weak or stronger protections against a Slapp suit. In many states, even if you are ultimately completely vindicated – if it’s shown that you know everything you said was truthful – you can still be required to pay for your defence, which can cost hundreds of thousands of dollars.

I knew that Representative Jamie Raskin, a Congress person from Maryland, had introduced federal anti-Slapp legislation. And so when we won the case, and I was able to take a breath … I reached out to his office. I was ultimately put in touch with a coalition that’s helping to advance anti-Slapp legislation. Protect the Protest is one of the coalitions I’m working with, and it includes folks like the Union of Concerned Scientists, Public Citizen and Amnesty International and many, many organisations. This group is trying to raise awareness of the impact of Slapp suits on individuals and it interviews environmental activists and scientists and all kinds of people who might be impacted, and we’ll be supporting this federal legislation when it’s reintroduced.

You recently won the early career researcher John Maddox prize – how did that feel?
It’s the greatest honour of my career. This is a prize that I’ve actually followed for many, many years. It was one of the sites that I went to soon after getting sued looking for stories because I’d never heard of any other scientists who’ve been sued. This is a good six or seven years of my life. And you have to be pretty persistent to do this stuff. At some point, you’re getting advice from well-meaning colleagues saying: “Why are you stressing yourself with this? Just let it go” – and you do question yourself. This is such validation that it matters to somebody. That the scientific community can recognise where you put your neck out there to do the right thing – and somebody noticed, and that felt wonderful.

• Valley Electronics did not respond to a request for comment