Since 1991, the number of retirees offered health benefits by the nation’s largest companies plummeted from 80 percent in 1991 to 56 percent by 2003, and some union retirees promised lifetime medical benefits have learned that lifetime only means “until revoked.”

Across the country in contract disputes and bankruptcy filings, federal courts have been pulled into the wrangling over how promises of lifetime benefits can be broken, or whether they existed at all. And the courts have not been uniform in their answers. Some predict that the U.S. Supreme Court will eventually have to step in to smooth out the wrinkles.