Pao, a former junior partner at the Silicon Valley venture-capital firm Kleiner Perkins Caufield & Byers, alleges that the firm discriminated against her. She is seeking sixteen million dollars in damages. Photograph by Eric Risberg / AP

Back in 1994, a trial in San Francisco Superior Court transfixed Silicon Valley. Three years earlier, a well-regarded partner at the Baker & McKenzie law firm, Martin R. Greenstein—the _Times _described him as “a swaggering bear of a man”—had gone out to lunch with colleagues. Outside of the restaurant, Greenstein had allegedly grabbed the breast of a legal secretary, Rena Weeks, dropped M&Ms down her blouse pocket, and asked her which of her breasts was larger. According to an account in the Times, Baker & McKenzie wrote a letter to the federal Equal Employment Opportunity Commission calling Weeks a “bounty hunter” and suggesting that she had an “extraordinary imagination” or had “irrationally misunderstood” what others considered “perfectly normal” behavior.

At the end of the trial, a jury awarded Weeks more than seven million dollars in damages, most of it from Baker & McKenzie and a small part from Greenstein himself, finding that the firm hadn’t appropriately responded to Weeks’s complaints. A state judge later cut the figure by half, but even that amount was seen as stunning. It was one of the biggest sexual-harassment awards ever, and it helped to revolutionize how businesses approach claims of harassment and other forms of discrimination.

Twenty-one years later, another discrimination case is unfolding in San Francisco Superior Court, and, again, people in Silicon Valley are rapt. The trial is the culmination of a lawsuit brought, in 2012, by Ellen Pao, a former junior partner at the venerable venture-capital firm Kleiner Perkins Caufield & Byers. (Pao is now the interim C.E.O. of Reddit. Advance Publications, which owns Reddit, is also the corporate parent of Condé Nast, the publisher of The New Yorker.) Pao alleges that the firm discriminated against her, and she is seeking sixteen million dollars in damages. In its broad outlines, the case echoes Weeks v. Baker & McKenzie: a high-powered Silicon Valley firm with a male-dominated culture, salacious allegations involving sexual conduct, millions of dollars in potential damages. But the two cases also highlight how significantly our understanding of discrimination has changed in recent decades.

The most significant development in anti-discrimination law was the passage of the Civil Rights Act of 1964, which includes the Title VII prohibition of discrimination; that’s where we got the now-familiar language barring discrimination “because of … race, color, religion, sex, or national origin.” But Title VII didn’t define discrimination, which meant that, in the years after its passage, the Equal Employment Opportunity Commission—which Title VII established—and various courts, including the Supreme Court, have been left to define the term themselves. Their definitions have evolved over time, along with social norms.

In the sixties, for instance, the commission said that a business refusing to hire or promote women because they were married or had children constituted illegal sex discrimination, unless men were similarly treated. Later, in 1971, the Supreme Court relied on that definition in an important case in which an employer told a woman that it wasn’t accepting applications from women with pre-school-aged children, though it employed men with children of the same age. (The Court decided in favor of the woman.) The treatment of sexual harassment as a form of discrimination—and one for which companies can be held responsible—has evolved over the years, too. This evolution has informed laws at the state level that echo Title VII, like California’s Fair Employment and Housing Act, under which both Pao and Weeks sued.

Yet some legal experts argue that the doctrine guiding many legal decisions about discrimination still hasn’t caught up with the realities of workplace gender relations; they refer to “second-generation discrimination” that is influenced by subtle, even unconscious, biases against women. The existence of such discrimination can be hard to prove to judges and juries, who typically require that plaintiffs prove that an employer had the intent to discriminate. Melissa Hart, a law professor at the University of Colorado at Boulder, said that there appear to be more complaints these days “involving challenges to subtle structural problems in the workplace.” In cases relating to this type of bias, plaintiffs have sought to bolster their arguments by introducing broader circumstantial evidence that the general cultures of their workplaces were hostile toward women. In one ongoing lawsuit against Goldman Sachs, two female former employees, who allege that women were paid and promoted differently from their male counterparts, described a boys’-club culture at the firm that included trips to strip clubs.

Pao, in her case against Kleiner Perkins, alleges that her standing at the firm deteriorated after she complained that a partner with whom she had been involved had retaliated against her, professionally, after the affair had ended. She argues, too, that the atmosphere at Kleiner Perkins was hostile toward women in general, and toward her in particular. On one occasion, she alleged, women were excluded from a dinner because the male partner organizing it figured that they would “kill the buzz.” Another time, a male partner gifted Pao, on Valentine’s Day, a book of Leonard Cohen poems that were illustrated with suggestive drawings. A great deal of time has been spent—on both sides—trying to establish what these kinds of incidents meant to those involved. Was the Cohen gift a sexual advance, as Pao believed, or a nod to a mutual interest in Buddhism (Cohen is a Buddhist), as a lawyer for Kleiner Perkins has suggested? When Pao received negative evaluations of her work following her affair, did that represent retaliation by the firm for her complaints of sexual harassment or an assessment of her performance that was free of gender biases?

Deborah Rhode, a law professor at Stanford, told me, “The sort of evidence you’re seeing in the Ellen Pao case is very typical of what’s out there in Silicon Valley. There are no smoking guns; much of it is what social scientists call micro-indignities—small incidents that viewed individually may seem trivial, but when viewed cumulatively point to a practice of insensitivity and devaluation that can get in the way of work performance.”

In the early days after Title VII and attendant state laws were passed, a great deal of discourse, in legal circles, focussed on how the law might be adjusted to account for our changing understanding of discrimination. These days, according to Hart, much of the interest has centered on how judges interpret existing laws or instruct juries to do so. Juries, for instance, are sometimes told to consider only whether discrimination was deliberate and willful (which may leave less room to consider unconscious biases), or whether an H.R. decision constituted discrimination or not (which leaves less room for considering situations in which discrimination was one factor, if not the only one). Some scholars have argued in favor of more nuanced instructions—for instance, allowing an incident to be defined as discrimination even if the people involved didn’t realize they were discriminating, or allowing that discrimination might have affected an H.R. decision even if other non-discriminatory factors also played a role.

Hart pointed to some of the language that Kleiner Perkins and its employees used to describe Pao’s problems at the firm: she wasn’t a team player, she raised her voice. In theory, these are traits that could make any employee look bad, but in practice, as social scientists have documented, discussions of these traits themselves have gendered implications. When a firm argues that a woman didn’t do well for these kinds of reasons, Hart said, “You need to stop and inquire, ‘What was meant by that?’ ”