Erratum.
In Colin Norman's article "The dark side of SDI" (News & Comment, 27 Feb., p. 962), the affiliation of Caroline Herzenberg was incorrectly given as Brookhaven National Laboratory. She is a member of the staff of Argonne National Laboratory. The paper she presented at the AAAS symposium in Chicago on 15 February was based on research conducted independently, and not with laboratory funding.