As the Columbia University student tells it, the encounter was harmless fun: A female freshman invited him into her suite bathroom, got a condom, took off her clothes and had sex with him. But as that young woman later described it to university officials, the encounter was not consensual. The university suspended him for a year.

He felt the outcome was unjust, but he did not know what to do about it. His lawyer, Andrew Miltenberg of Manhattan, did.

Invoking Title IX, the federal gender-equality statute that is typically used to protect the rights of female students, he sued Columbia, saying his client had been “discriminated against on the basis of his male sex.”

At a moment when students who have been sexually assaulted are finding new ways to make their voices heard, and as college officials across the country are rushing to meet new government standards, a specialized class of lawyers is raising its voice, too. They are speaking out on behalf of the students they describe as most vulnerable: not those who might be subjected to sexual assault, but those who have been accused of it.