LISTEN: Who decides criteria for which female athletes are tested for variations in sex biology?

Bill Burton: It's a complicated and important story. And of course, many are going to be watching these athletes soon competing in the Paris Olympics. So what's the official stated purpose of this testing? And who's deciding on what to test for?

Rose Eveleth: It's a great question. The rules are in place, because the governing body of track and field, which is the sport that I mostly cover in this series, they are of the opinion that some women with certain variations in sex biology have an unfair advantage over other women on the track. And that in order to account for that those women need to change their body, change their biology in order to basically remove that advantage to create a quote unquote, level playing field. And so that is the purpose of the regulations. The testing is done in a sort of, interestingly, opaque way. It's not always clear why certain athletes get tested and why other athletes don't. This is not like doping, where there are some pretty clear regulations, the doping regulation book is, you know, thousands of pages, it's this huge binder. It's one of the critiques I think, around this is that it is quite opaque.

BB: The results of these tests, though, what do they actually tell us? Don't they really just lead to more questions?

RE: Yeah, in a lot of ways they do. The tests are pretty extensive. If you are flagged for potential regulation under these eligibility policies, because of the way the policies are written, they only apply to a very specific subset of DSD's, or differences of sex development, which is the sort of medical term for variations in sex biology. It kind of lists out certain conditions and the rules only apply to some of those conditions. And so in order for you to know if you are an athlete that falls under these regulations, you actually need to go through a fairly extensive medical workup. To know things about like your internal anatomy, your circulating testosterone, you have to do an ultrasound, you have to do a psychological, you know, there's all sorts of tests that they want to do. And many of the athletes that I've spoken with who've had these tests find them incredibly confusing, quite invasive, don't totally understand why they are being tested in this way, why they're having to go through such extensive examinations. And the reason, the stated reason is because you need to know if they have this very specific condition or diagnosis, which I think raises some interesting medical ethics questions. Right. I spoke with a medical ethicist to talk a lot about the right not to know right, we have a right to not know about certain things if we don't want to.

BB: You quite literally traveled the world for this podcast, talking with athletes, officials, scientists, do you feel we're getting any closer to what is fair? And who even gets to determine what fair is?

RE: Well, I think we will the sun will explode before humans have decided what's fair. It's subjective, right? It's totally subjective. You and I might have different ideas about what's fair. And even people who I think are generally maybe on quote unquote, the same side or who agree about many things might have different opinions about where exactly that line is. One of the things that I thought was really interesting in researching this project and talking to so many people is there is also this sense that there should be just a test for fairness, we should just be able to like do a swab or do an experiment and that will tell us what to do. And unfortunately, that's not how it works. You know, science can get us closer. Science can tell us things that are useful pieces of information in order to decide how we feel about the world and what is fair and what is just but it actually can't take that burden off of us as people in terms of the decision making.

BB: Rose Eveleth is the host of the podcast, "Tested: A surprising history of women's sports." It's a collaboration between the CBC and NPR's Embedded.

This transcript was edited for clarity.