CHICAGO (AP) — The U.S. Supreme Court hears a case next week that challenges health insurance subsidies that make coverage more affordable for more than a quarter-million Illinois residents.

The issue rests on the interpretation of four words in President Barack Obama’s health care law.

The challengers argue the law provides subsidies only to people who get their insurance through an exchange “established by the state.” About three dozen states — including Illinois — have not established their own marketplaces and instead rely on the federal HealthCare.gov system.

Illinois Attorney General Lisa Madigan has signed onto an amicus brief with 21 other states in support of the subsidies.

Gov. Bruce Rauner spokeswoman Catherine Kelly says the governor’s office “will take appropriate action depending on how the Supreme Court rules.”

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