Papers relating to Steinberg's difficulties in government clearance during the late 1940s and the 1950s, owing to his association in research while at McGill University with a chemist who later proved to be a spy for the USSR. A horrendous example of "guilt by association," which neither his excellent record of wartime research with OSRD, nor his scientific reputation, nor his friends' and colleagues' testimonials could quickly overcome. Also includes an autobiographical sketch.