With each court ruling, the secret testimony that a Chicago grand jury heard during World War II edges closer to public scrutiny. If that testimony is unsealed, all of us will know more about the government's only effort to prosecute the news media for an alleged violation of the Espionage Act of 1917. The journalists in the dock? Our predecessors at the Chicago Tribune.

This as yet unfinished yarn traces to the U.S. Navy's ambush of an Imperial Japanese navy strike force near Midway Island. The little atoll halfway between Asia and North America was a steppingstone in Japan's plan to seize the Hawaiian Islands. As the U.S. neared victory on June 7, 1942, the Tribune published a front-page scoop, "Navy Had Word of Jap Plan to Strike at Sea." The story reported the size and schedule of Tokyo's armada. The story's richness of detail strongly implied (without stating explicitly) that Washington had cracked Japan's secret naval code: The Tribune evidently had obtained the Japanese plan from an official U.S. source — someone who had access to decoded Japanese secrets.

The Tribune's tacit revelation of the code-breaking coup infuriated Washington. President Franklin Roosevelt wanted to have Marines occupy Tribune Tower. Under pressure from Roosevelt and Navy officials, a special prosecutor impaneled a federal grand jury here to consider espionage charges against reporter Stanley Johnston, managing editor J. Loy Maloney and the Tribune itself. The grand jurors decided not to indict. But for 74 years the testimony they heard from some 13 witnesses — including naval officers and staffers from the Tribune and two other newspapers that ran its story — has remained sealed.