The subsidies at the heart of an Obamacare dispute are back in court today. In April, we described the stakes for the case, and the preferences of the players. Now that the case has reached a possible turning point, we’ve updated our analysis.

Cost-sharing reductions seem like an arcane aspect of the Affordable Care Act, but they could now make or break the Obamacare insurance marketplaces. Even President Trump has been talking about them, as a possible bargaining chip to help pass the Republican health bill in Congress.

Insurance companies rely on these payments when selling Obamacare policies, which is why President Trump has said that withdrawing them would destabilize markets. (“Obamacare is dead next month if it doesn’t get that money,” he told The Wall Street Journal in April.) On Monday, lawyers from both sides of a case about the payments have asked to delay making a decision about them. That means there will be no immediate change in policy, but it leaves open the possibility that the Trump administration will still halt the payments.

What exactly are the cost-sharing reductions?

The Affordable Care Act helps make health insurance affordable for low-income people in two ways. The government provides a subsidy to help buy a policy, but about seven million people also get help with their out-of-pocket costs when they go to the doctor or fill a prescription. The government pays the insurance companies extra — $7 billion last year — to offer plans with discounts on the usual deductibles and co-payments that might make medical care unaffordable for relatively poor consumers.