In an important decision that could impact the health care of millions of people, the Supreme Court decided this week that it will consider the latest Affordable Care Act (ACA) case in its next term. This decision to hear the case follows a January decision not to take a fast-track approach to the lawsuit. Though the timeline for the hearings has not been set, the court is likely to hear oral arguments this fall, possibly as early as October. A decision on the case would not be likely before 2021.

The lawsuit claims that the ACA is unconstitutional because Congress reduced the individual mandate penalty to zero in the 2017 tax bill. Though this argument was dismissed by many legal scholars, the district court found in favor of the plaintiffs, and the Trump administration endorsed this ruling and fully supports the lawsuit. An appeals court last year agreed with the district court, at least in part.

Those defending the health law urge the Supreme Court to act quickly, arguing that the prolonged uncertainty over the ACA’s fate could damage the nation’s health care system and put patients at risk. Importantly, however, the ACA remains in place as the case proceeds.

The ACA’s impact on the entire health system cannot be overstated, and the risks for older adults and people with disabilities would be devastating if the law were overturned. The ACA improved Medicare by expanding coverage for preventative care, limiting costs, and closing the Part D donut hole. Each of these improvements would disappear if the ACA were overturned.

If the plaintiffs succeed, the lawsuit would also end requirements that health insurance cover pre-existing conditions. This could leave some or all of the estimated 133 million Americans under 65 with pre-existing conditions without affordable coverage. In addition, it would mean the return of lifetime caps on coverage and of the overly punitive “age tax” for older people seeking to purchase insurance.

Perhaps most significantly, the lawsuit would eliminate the Medicaid expansion that has improved coverage, access to care, and economic outcomes for low-income adults.

The Affordable Care Act has led to huge gains in coverage for millions of Americans and has improved the lives of people with disabilities, older adults, and families. We strongly urge states and the Trump administration to abandon efforts to undermine the ACA, and to instead work together to improve health care and coverage for all Americans.

Read more from Medicare Rights about the ACA’s coverage expansions and consumer protections.

Read more about the Supreme Court’s decision to hear the case this fall.