When a B-29 bomber exploded over Georgia in 1948, the victims' families were denied access to crucial information relating to the accident because the federal government claimed such access would endanger national security. When the Supreme Court upheld that claim in United States v. Reynolds (1953), a new precedent was established, allowing the executive branch to assert an all-encompassing "state secret privilege" as a basis for withholding information from public scrutiny.

For more than fifty years that decision has been viewed with apprehension by a great many scholars and...