Michael A. Hardy, a fervent civil rights lawyer who for more than three decades defended the Rev. Al Sharpton as his faithful counsel and confidant, died on Monday in Manhattan. He was 69.

His death, in a hospital, was announced by the National Action Network, the Harlem-based civil rights organization that Mr. Sharpton founded in 1991. The cause was cancer. Mr. Hardy had served as its general counsel and executive vice president almost from its inception.

Mr. Hardy was notably involved in defending Mr. Sharpton in a defamation lawsuit brought by a local prosecutor whom Mr. Sharpton had said was one of six white men who kidnapped and raped Tawana Brawley, a 15-year-old Black girl, in upstate New York in 1987. A grand jury determined that Ms. Brawley’s account was a hoax.

Mr. Hardy’s legal dexterity also figured in successful challenges to the New York Police Department’s stop-and-frisk strategy, which its critics said unfairly targeted Black and Latino men. And his work helped lead to bans against certain methods of police restraint in the wake of the chokehold death of Eric Garner, an unarmed Black man who was stopped on a Staten Island sidewalk in 2014 on suspicion of illegally selling cigarettes.

“When Michael started, it was unheard of to get police prosecuted; at the end of his life we see police getting convicted,” Mr. Sharpton said in a phone interview. “He was the legal mind of the 21st century civil rights movement.”

At first glance, Mr. Hardy and Mr. Sharpton seemed an unlikely duo. Mr. Sharpton grew up in a poor, predominantly Black neighborhood in Brooklyn, attended public schools and briefly enrolled in Brooklyn College. Mr. Hardy hailed from a middle-class Brooklyn family and was educated in prestigious and overwhelmingly white institutions: Northfield Mount Hermon, a preparatory school in Massachusetts, and Carleton College in Minnesota.