The Republican-led states are trying to prove they were harmed by the 2010 health law—and thus have “legal standing”—because their Medicaid costs increased, even though Congress eliminated the penalty for not having health coverage in 2019. At least one justice was skeptical.

Attorneys for GOP-controlled states seeking to kill the Affordable Care Act (ACA) told the Supreme Court last week that at least some of the 12 million people who newly enrolled in Medicaid signed up only because of the law’s requirement that people have insurance coverage—although a tax penalty no longer exists.

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The statement drew a rebuke from Justice Sonia Sotomayor, who said it belies reason. Several health experts also questioned the argument that poor people apply for Medicaid not because they need help getting health care but to meet the ACA’s individual mandate for coverage.

The point is vital to the Republicans’ case to overturn the ACA, an effort supported by the Trump administration. The states are trying to prove they were harmed by the 2010 health law—and thus have “legal standing” to challenge its constitutionality. They argue their Medicaid spending increased because of the mandate, even though Congress eliminated the tax penalty for not having health coverage in 2019. Even when the penalty existed, most poor people were exempt because of their low income.

Under the ACA, states can opt to expand Medicaid eligibility to all adults earning less than 138 percent of the federal poverty level, or about $17,600 for an individual. States and the federal government share the cost of their care.

If the states cannot prove they have standing, the justices can toss their case without ruling on its merits. The case also involves two individuals who purchased private insurance from Texas and are suing to have the law overturned.

The Medicaid costs issue was one of several ways Texas and other GOP-controlled states participating in the lawsuit say they were harmed by the ACA even after the individual mandate penalty was reduced to zero. Several justices, including conservatives Clarence Thomas and Amy Coney Barrett, posed questions about whether the states had standing.

The case heard last Tuesday, California v. Texas, was the third time the high court has taken up a major suit on the ACA. Republican attorneys general in 18 states and the Trump administration want the entire law struck down, a move that would threaten coverage for more than 20 million people, as well as millions of others with preexisting conditions, including COVID-19.