Ellen Pao walks to a courtroom in San Francisco Superior Court in San Francisco, California, March 2, 2015. Photo: Robert Galbraith/Reuters/Corbis

It happens all the time when my husband and I are at work events together. Cocktail Party Guy asks my husband about how things are going at his news site, and he answers. Then Cocktail Party Guy asks me how our dogs are, and I answer, before pivoting the conversation back to work — and later rolling my eyes as we walk away. It is not impolite. It is not inappropriate. But it is still, at least in my mind, sexist. Both me and my husband love our work. Both me and my husband love our dogs. One of us gets asked about our work. One of us gets asked about our dogs.

It is a form of soft discrimination that I fear might be all too familiar to all too many women — and often I find it hard to explain to my male friends and colleagues. Occasionally, I even find myself struggling to convince them that it is discrimination, and that it has consequences.

Related Stories The Real Lesson of the Ellen Pao Verdict

I found myself going back to those moments with Cocktail Party Guy while following Ellen Pao’s lawsuit against her former employer, the powerhouse venture-capital firm Kleiner, Perkins, Caufield and Byers. In the suit, Pao argued that the firm failed to promote her because of her gender. But it was not a cut-and-dry case. Much of it centered around those Cocktail Party Guy moments, ones where one reasonable observer might see nothing going on and another reasonable observer might see clear evidence of sexism.

Exhibit A: Pao’s performance reviews knocked her for her “sharp elbows.” There were similar negative comments in Pao’s male colleagues’ reviews, but they were nevertheless promoted. Does that demonstrate that Kleiner Perkins treated Pao differently because she was a woman? Might they have interpreted her assertiveness as “bitchiness,” and her male colleagues’ assertiveness as “strength” or “conviction”? Maybe she really did have sharp elbows, hurting her relationships with clients? Can’t women ever be criticized for being caustic?

Exhibit B: Some of Pao’s male colleagues were invited on a skiing trip. Pao was not. “The issue is that we are staying in condos, and I was thinking that gents wouldn’t mind sharing, but gals might,” Pao’s colleague wrote in an email. “We can add 4-8 women next year.” But it was a social event held outside work hours. Does it really demonstrate anything about the culture of the firm?

Exhibit C: John Doerr, Pao’s biggest champion in Kleiner Perkins, described looking for investments. If you take the founders of Amazon, Google, and Netscape, he said, “They all seem to be white, male nerds who’ve dropped out of Harvard or Stanford and they absolutely have no social life. So when I see that pattern coming in — which was true of Google — it was very easy to decide to invest.” But is that indicative of bias within the company?

It went on and on like that. The trial dredged up dozens of messy incidents that could be interpreted as sexist, or not. Pao’s attorneys argued that they were indicative of a discriminatory corporate culture, one that punished women for their ambition rather than promoting them for it. Kleiner Perkins argued that Pao just did not make the cut. She failed because she “lacked the ability to lead others, build consensus, and be a team player.” Ultimately, the jury sided with Kleiner Perkins. Pao did not prove her case, and she lost on all counts.

But reading through the trial testimony and court documents, it is impossible not to see a crummy culture, if not an overtly sexist one. And the problem is that sexism today very often is not overt. It’s subtle, and that makes it all the more difficult to identify and root out. It’s not your boss hitting on you and then demoting you to secretary when you spurn his advances. It’s your boss describing your assertiveness as too assertive, and suggesting you might be better suited for an operational role. It’s not your being asked to fix the coffees at a client meeting. It’s Cocktail Party Guy forcing you to return the conversation to business, so you have an opportunity to develop him as a source rather than talking about dogs for 20 minutes.

It is pervasive. It is persistent. And it is so, so exhausting, all those subtle hints that you are a little different and that your behavior is being interpreted a little differently. On top of that, it does have profound consequences, if made through a million tiny cuts. This is from one Harvard review of the literature on sexism in high-powered workplaces:

In simulated work settings, powerful men often behave in patronizing ways toward their female subordinates, giving low-power women fewer valued resources than low-power men but praising those very same women more than the men. Likewise, field research has documented parallel anti-female biases in the quantitative evaluations used as the primary determinant of promotion for Wall Street lawyers … Importantly, when treated in patronizing ways by powerful men, low-power women reported more anger, perceived less personal control over outcomes, and performed worse. In fact, in masculine domains, the patronizing behavior of powerful men created gender differences in performance on a standardized math test where such differences did not otherwise exist. Whereas low-power women are often praised in ways that make it difficult for powerful men to see the co-existence of group-based inequities in the allocation of limited resources, some findings suggest that women who threaten power in masculine domains may become the targets of aggression.

Subtle sexism results in women getting fewer opportunities at work. It hurts their performance. It results in them receiving worse evaluations. It even opens them up to “aggression” in the workplace. Ultimately, the Harvard authors conclude, it leads to women being “perceived as interchangeable objects, [who] lack basic humanness, and underperform.” The literature does not need Ellen Pao to prove it in a court of law.

But there is one very clear lesson we should draw from the murk of her case. Pao did not sue just because she felt that Kleiner Perkins fostered a sexist corporate culture. She sued because she felt that the culture prevented her from ascending in the firm, costing her work opportunities and hundreds of thousands of dollars.

How to stop pernicious, subtle sexism, if you cannot prove it in the courts? Pao simply driving attention to the issue might help, as my colleague Ann Friedman notes. So would making the metrics in performance evaluations more objective and transparent. Had Kleiner Perkins made its promotions based on how much business its employees brought in, rather than whether they “demonstrated leadership,” it might have treated her differently. The idea is to force covert sexism to be made overt where you can, around the conference table if not at the ski lodge or the cocktail party. Only then can you stamp it out.