The Supreme Court on Thursday agreed to let an insurance company settle some asbestos lawsuits for about $500 million in exchange for blocking any future litigation resulting from its long relationship with Johns Manville Corp., once the world's largest producer of asbestos.

Travelers Cos. had been named in lawsuits alleging that it tried to hide dangerous health effects of asbestos. The company argued that asbestos claims must be paid out of a trust created by Johns Manville in the 1980s and approved by a federal bankruptcy judge.

Asbestos is a mineral that was commonly used until the mid-1970s in insulation and fireproofing material. Exposure can increase the risk of lung cancer, mesothelioma and other ailments, according to federal health agencies.

Travelers settled with several groups of plaintiffs in 2004 with the caveat that federal courts make clear the company would not have to face any new similar lawsuits. The 2nd U.S Circuit Court of Appeals overturned lower-court approval of the settlement, saying a bankruptcy judge lacked the authority to act so broadly.

The high court on Thursday overturned that decision and sent the case back to the New York-based federal appeals court.