ASHINGTON, July 24 — The Bush administration has been going to court to block lawsuits by consumers who say they have been injured by prescription drugs and medical devices.

The administration contends that consumers cannot recover damages for such injuries if the products have been approved by the Food and Drug Administration. In court papers, the Justice Department acknowledges that this position reflects a "change in governmental policy," and it has persuaded some judges to accept its arguments, most recently scoring a victory in the federal appeals court in Philadelphia.

Allowing consumers to sue manufacturers would "undermine public health" and interfere with federal regulation of drugs and devices, by encouraging "lay judges and juries to second-guess" experts at the F.D.A., the government said in siding with the maker of a heart pump sued by the widow of a Pennsylvania man. Moreover, it said, if such lawsuits succeed, some good products may be removed from the market, depriving patients of beneficial treatments.

In 2002, at a legal symposium, the Bush administration outlined plans for "F.D.A. involvement in product liability lawsuits," and it has been methodically pursuing that strategy.

The administration's participation in the cases is consistent with President Bush's position on "tort reform."