Harry Wu, the former Chinese political prisoner died Tuesday at 79. In the 1990s, Mr. Wu used his personal experiences and research to bring the matter of forced labor—and the products they exported to the West—into the then vigorous American debate over human rights in China. Thanks to Mr. Wu, the word "laogai" referring to a vast system of prison labor camps entered the vocabulary much as the term "gulag" had for the Soviet Unions two decades before.

The educated son of a Shanghai banker and his wife, Mr. Wu was sentenced to jail for 19 years at the age of 23 for speaking out against invasion of Hungary by the Soviet Union, then a Chinese ally. He survived prison by becoming "a beast." A prisoner could become a "millionaire" by tracking rats and finding a store of seeds, corn and grains of rice. Finding a live rat was even better.

After Mao's death eased the political climate, in a fluke, he was invited to visit a California university. An American professor had seen an article of his, published in France, about a geological device. That got him to the United States, but lacking financial support, he worked odd jobs to get by, including making doughnuts on the night shift.

Unable to forget his comrades, he visited China surreptitiously to gather information on conditions and Western businesses' reliance on forced labor. In 1995, he was detained as he tried to enter China at a Kazakhstan border crossing. His work was certainly known to the Chinese. He'd collaborated with CBS's 60 Minutes. Nevertheless, his friend and colleague Jeff Fiedler, the labor union official, rejected the notion that Mr. Wu was reckless. Wu was "truly the moral voice about the Chinese gulag … to him, there was no choice but to go back."

His fate was uncertain, and possibly dire. American diplomats were refused consular access. However, Wu later said he felt relief when he was charged with espionage, even though a conviction might have meant the death penalty. The Chinese were acknowledging he was in custody, and planned to use him as a bargaining chip. After several more weeks, and intense international pressure, he was expelled. U.S.-China relations got back to normal. Hillary Clinton went to the Beijing women's conference that September.

Mr. Wu knew that it was his American citizenship that saved him and guaranteed him decent treatment in a jail. "Your food, same as mine," the warden told him. He was grateful, but he didn't let the US off the hook. America had influence, and a role to play. He didn't think much of the idea that trade and investment by themselves would change China's human rights performance and opposed abandoning pressure. "Tell the Chinese leader, 'you want the money?'" You have to improve your human rights."

Harry was a tough guy, but he insisted he was not special. He could have died, as so many of his fellow inmates had. In that interview with Charlie Rose he said: "Many many of them, same as me, but they are nameless and faceless today. Nothing different. I'm just lucky." Maybe.