Back in the 1930s, you could walk into a press box and find not just a social justice warrior but an actual communist. His name was Lester Rodney, and he wrote sports for the party newspaper, The Daily Worker. Rodney’s politics made his life complicated. Writers at “respectable” outlets like The New York Times would hardly speak to him. But his moral clarity was keener than just about anybody’s.

“I can do a lot of things you guys can’t,” Rodney told colleagues, according to his biographer Irwin Silber. “I can belt big advertisers, automobile manufacturers, or tobacco companies. … You guys can’t write anything about the ban against Negro players. I can do that.”

Indeed, the segregation of baseball — “The Crime of the Big Leagues!” the Worker called it — was Rodney’s great subject. He was determined to exact justice on the sports page. Rodney pestered owners and managers about their willingness to sign black players and recorded their responses. The pitcher Satchel Paige used Rodney’s column to challenge the winners of the World Series to a game against a Negro Leagues all-star team.