Days after the insurance lobby began an aggressive campaign against a Senate plan to overhaul the nation's healthcare system, senior Democrats threatened to revoke the industry's long-standing antitrust exemption. Health insurance is one of only a few industries exempted from certain federal antitrust regulations, and Sen. Charles E. Schumer (D-NY) said the exemption was "one of the worst accidents of American history. It deserves a lot of the blame for the huge rise in premiums that has made health insurance so unaffordable."