The Justice Department is conducting an investigation to determine whether the A. H. Robins Co. criminally obstructed justice during lawsuits brought by women who charged that they had been harmed by the Dalkon Shield intrauterine device, sources told the Washington Post. No one in the Justice Department would comment on whether an inquiry was under way. A Robins spokesman said the firm was not aware of any such probe. There have been several allegations during the litigation that Robins had provided false testimony or withheld information from plaintiffs. In 1985, a federal appeals court ruled that a Robins expert witness had given false testimony in a Tampa, Fla., trial.