The three stories are nearly identical. A young woman arrives at Columbia University for her doctoral studies, eager to prove herself as a scholar. A star professor’s attentions seem to indicate she has succeeded. The attentions soon turn sexual, and the student grows uncomfortable. But she feels powerless to speak out.

The difference in the stories is the decade in which they took place. Jennifer Sheridan Moss said she was harassed by William V. Harris, a renowned Greco-Roman historian, in the 1980s. Jennifer Knust said he harassed her in the 1990s. And an anonymous graduate student, identified in court papers as Jane Doe, said he harassed her in the 2010s.

The women’s stories of alleged harassment — and in particular of how Columbia and other professors responded to them — shed light not only on one powerful man’s behavior over the years, but also on changing mores in academia, and the shifting understanding of universities’ responsibility to enforce them.

Graduate students and professors work together with a high degree of intimacy, and the power dynamic between them is often fraught. But only recently have rules been put in place to regulate whether their relations can tip over into sexual interactions. For decades, Columbia discouraged romantic relationships between professors and students they supervised, but it did not explicitly ban them until 2012.

“At the time, it was a certain level of cultural understanding that female students were available to professors,” Dr. Moss said of her experience with Dr. Harris in the 1980s.