John W. Powell, an American journalist who in 1959 was tried for sedition in a rare and highly public case after he asserted in print that the United States had used biological weapons in the Korean War, died on Monday in San Francisco. He was 89 and had lived in San Francisco for many years.

The cause was complications of pneumonia, his son John S. Powell said.

Mr. Powell’s case was one of the rare federal prosecutions for sedition — inciting resistance to the government — in the decades since World War I. Though the government eventually dropped all charges against him, his case dragged on for five years and became a cause célèbre....

Even today, historians do not agree on whether the United States actually used biological weapons in North Korea, as Mr. Powell contended more than half a century ago.

“There’s no consensus,” Stephen Endicott, a retired professor of history at York University in Toronto, said Tuesday in a telephone interview. Mr. Endicott is the author, with Edward Hagerman, of “The United States and Biological Warfare: Secrets From the Early Cold War and Korea” (Indiana University, 1998).

Mr. Endicott added:

“Nobody has come forward to say, on the American side, ‘Yes, we did it,’ or on the Chinese side, ‘Yes, we lied about it.’ It remains one of the controversial issues of the cold war.”