Could you explain?
Bear in mind this was eight or more years ago, the arguments were more legal than actuarial, and I just work with the practical implications of gender-neutral pricing, so I may be a bit hazy on the details...
I just read this as a bit of a refresher: www.cliffordchance.com/content/dam/cliffordchance/briefings/2011/03/client-briefing-on-testachats-case-judgment.pdf
(By the way, reading it back, it's interesting how sex and gender are used interchangeably, but without any contortions about transgender, seeing the world as made up of men who are male and women who are female - goodness knows how it would be interpreted today).
So, EU allowed an exception to gender-neutral pricing for insurance, and the court ruling was basically that you can't have an exception which has no time limitation, so EU Commission had to lapse that particular exception.
There was then talk at the time whether the Commission would introduce something in its place that would allow differential pricing on the basis of actuarial evidence, but nothing came of that as far as I recall.
But I think there was debate about whether there is anything inherent in male / female biology that makes women less risky as drivers, or whether male / female correlates to something else - in which case, motor insurers should be underwriting on the basis of that "something else". For example, if what makes "boy racers" risky is that they go out more at night and drive fast on country roads, then what you should rate on is how much a driver goes out at night and what sort of roads they drive on - I believe that's where those car tracking devices are a selling point, where the insurer will charge your premium on the basis of actual driving experience. But I don't work in motor insurance, so I'm not sure how that's working in practice.
In my area (annuities), there was some debate over whether women's longer life expectancy is down to biology or some other correlate, but for selling annuities I think the industry has just come to accept the use of unisex rates. When we set out reserves, we do take account of sex, because the data shows us females live longer and it would have significant financial implications if we ignored the sex-based distinction. (If there's evidence that if I put on a dress, take some hormones and call myself a woman, then I'll live longer, then maybe I should consider it
).