Over the course of one week in early October, Sanford A. Rubenstein appeared on the front page of The New York Post four days in a row. It was a lot — even for him.

Mr. Rubenstein, a civil rights lawyer who has handled some of New York’s most explosive cases of police brutality over the years, has been featured so often on the city’s tabloid covers that some have joked he owns a time share there. But this run of publicity was different. The noisy headlines in 180-point type did not describe him as what he had been for decades: a man who fought the police on behalf of victims’ families. They described him as what he had become: a man accused of rape.

On Oct. 1, Mr. Rubenstein, who is 70, showed up at the Four Seasons restaurant for the gala 60th-birthday party of a longtime friend and collaborator, the Rev. Al Sharpton. He spent the evening milling under balloons in a crowded ballroom with Spike Lee, Aretha Franklin and Mayor Bill de Blasio. When he went home, two women went with him. One spent the night: a 43-year-old board member of the National Action Network, Mr. Sharpton’s civil rights group. The next morning, her lawyer Kenneth J. Montgomery said, the woman woke feeling “foggy” and discovered Mr. Rubenstein sexually assaulting her. There were bruises on her arms, Mr. Montgomery said, and condoms on the floor; she later experienced vaginal bleeding.

From the start, Mr. Rubenstein has forcefully denied the allegations, mainly through his own lawyer, Benjamin Brafman, who maintains that the encounter was consensual and that his client suffered in its wake. Within days of the complaint, and though no charges had been filed, photographs were published of investigators hauling evidence — including a mattress — from Mr. Rubenstein’s penthouse on East 72nd Street in Manhattan. Unflattering descriptions of his body and his sex life appeared in the news after a series of humiliating leaks.