The first time Republicans asked the U.S. Supreme Court to take a sledgehammer to the Affordable Care Act, they failed. The second time didn’t turn out well for the health care law’s GOP opponents, and the ACA survived the third effort, too.

Will the fourth time be the charm? The Associated Press reported:

The Supreme Court agreed Friday to consider reinstating some preventative care coverage requirements under the Affordable Care Act that were struck down by a lower court. The federal government appealed to the high court after the 5th U.S. Circuit Court of Appeals sided with employers who argued they can’t be forced to provide full insurance coverage for things like medication to prevent HIV and some cancer screenings.

For those who might benefit from a refresher about this case, let’s revisit our earlier coverage and review how we arrived at this point.

It was nearly two years ago when Judge Reed O’Connor of the Northern District of Texas — a judge who has earned a reputation as one of the judiciary’s most far-right jurists — blocked enforcement of the ACA’s preventative health care requirements, jeopardizing everything from cancer screenings to vaccinations, prenatal services to HIV prevention, pap smears to heart disease screenings.

Last year, the 5th U.S. Circuit Court of Appeals, generally seen as the nation’s most conservative appellate bench, predictably agreed with O’Connor and rejected the ACA’s health task force and its authority to require insurers to cover an array of preventive health interventions and screenings.

It’s worth emphasizing that in the first three ACA cases at the high court, the law known as Obamacare faced existential threats: The plaintiffs were trying to tear down the entire system, root and branch.

That’s not the case in this new dispute. That said, as The New York Times’ report explained, the impact of a potential defeat at the U.S. Supreme Court would be dramatic for millions of Americans.

The new challenge is directed at a task force that decides which treatments are covered. It has determined that insurers must pay for, among other things, screenings to detect cancer and diabetes; statin medications to reduce the risk of heart disease and strokes; physical therapy for older adults to prevent falls; and eye ointment for newborns to prevent infections causing blindness. The law’s requirement of coverage for lung cancer screenings alone saves more than 10,000 lives each year, the Biden administration told the justices.

This comes against a backdrop of otherwise excellent news for the Affordable Care Act: The reform law’s enrollment totals have reached all-time highs, and public-opinion research has found that the ACA has never been more popular.

But as congressional Republicans eye measures that would make health security far more expensive, and Republican-appointed Supreme Court justices consider the future of preventive care policies, there are ominous clouds on the horizon.

This post updates our related earlier coverage.