Makers of medical devices, such as implantable defibrillators or breast implants, are immune from liability for personal injuries as long as the device is approved by the FDA before it is marketed and it meets the agency’s specifications, the Supreme Court ruled last week.

The 8-to-1 decision was a victory for the Bush administration, which for years has sought broad authority to preempt tougher state regulation.

In 2004, the administration reversed long-standing federal policy and began arguing that “premarket approval” of a new medical device by the FDA overrides most claims for damages under state law. Because federal law makes no provision for damage suits against device makers, injured patients have turned to state law and have won substantial awards.

The Bush administration will continue its push for preemption in another FDA case that the court has accepted for its next term, on whether the agency’s approval of a drug, as opposed to a device, preempts personal injury suits. Drugs and medical devices are regulated under separate laws.

The case before the court concerned only medical devices that had gone through the premarket approval process specified by the Medical Device Amendments of 1976. Most devices now available reached the market through a different process, under which the FDA found them to be “substantially equivalent” to those marketed before the 1976 law took effect.

It was not immediately clear how many of the thousands of lawsuits against medical device manufacturers would be affected, though some pending cases will almost certainly be nullified.

The decision, for example, does not foreclose lawsuits claiming that a device was made improperly, in violation of FDA specifications. Cases may also be brought under state laws that mirror federal rules, as opposed to supplementing them.