Federal regulators are proposing to insert language in a prescription drug rule that officials in some states believe would help pharmaceutical companies fight off lawsuits.

The proposal comes amid a flurry of high-profile, state and federal pharmaceutical liability cases, including a mounting numbers of cases involving the painkiller Vioxx, made by Merck & Co.

The National Conference of State Legislatures revealed the proposal last week in a press release and letter sent by its president to Health and Human Services Secretary Mike Leavitt. Both were first reported Saturday by The Wall Street Journal.

The new language reportedly appears in the preamble to a proposed rule that guides the labeling of prescription drugs, first proposed by the Food and Drug Administration more than five years ago. The inserted language claims that the revamped and federally approved labels on prescription drugs would pre-empt state law.

"This attempt to insert pre-emption language is a thinly veiled attempt on the part of FDA to confer upon itself authority it does not have by statute and does not have by way of judicial ruling," National Conference of State Legislatures President Steve Rauschenberger wrote in his letter to Leavitt.

The group wants either the language to be withdrawn or the FDA to reopen the public comment period for the proposed rule, first announced in December 2000. The group said it initially agreed that the proposal didn't contain provisions that would trump state or local laws.

The FDA declined to comment Tuesday.

The FDA wants to overhaul the fine-print warnings on prescription drugs intended for doctors and patients. The revised drug warnings, as originally proposed, would lead off with a user-friendly "highlights" section that includes the most important warnings for each drug.