Requiring workers who smoke to pay more for health insurance violates the Employee Retirement Income Security Act by unfairly targeting employees because of their health status, according to the suit.

The talks come amid ongoing pressure from the federal government to control Medicare costs that have eaten away at Humana's finances and market value.

These are the states with the highest percentages of working-age adults who reported having seen a dentist in the previous 12 months, according to the CDC.