The U.S. Supreme Court today will consider how much of PresidentBarack Obama's health-care law must be thrown out if the justicesdecide Congress can't require Americans to buy medicalinsurance.

The debate on so-called severability took on added significanceafter questions from justices yesterday indicated a majority mightstrike down the insurance requirement. Today's session willconclude three days of hearings, six hours in all, the longest in44 years.

The impact of the coverage mandate on the rest of the law isamong the most important issues for the health-insurance industry.If the court strikes down the requirement, insurers want thejustices to toss out provisions that forbid them from refusingcoverage or charging higher premiums to people with pre-existingconditions.