The case may well make its way to the Supreme Court.

Does the ruling change anything for open enrollment?

The case could threaten the survival of the landmark health law and, with it, health coverage for millions of Americans, protections for people with pre-existing conditions and much more.

But for now, open enrollment is proceeding as planned.

The case is “still moving through the courts,” the Centers for Medicare and Medicaid Services said in an email on Saturday. “The marketplaces are still open for business, and we will continue with open enrollment. There will be no impact to enrollees’ current coverage or their coverage in a 2019 plan.”

But any confusion caused by the Texas court decision could contribute to lower enrollment numbers, which were already lagging behind last year’s turnout.

Why are open enrollment numbers down this year?

From when open enrollment started, on Nov. 1, to Dec. 8, sign-ups in the 39 states that use HealthCare.gov were down about 12 percent compared with the same period last year.

There are a few reasons enrollment has been lower this year. In states with Medicaid expansion, residents may rely less on the federal marketplace for health insurance. In addition, Congress eliminated the tax penalty for people who go without coverage, lifting pressure off people who only bought coverage under threat of a fine. There may also be less awareness about the sign-up deadlines. The Trump administration slashed funding for advertising and other forms of marketing by 90 percent last year, and those funds were not restored.

Now, add in the last-minute confusion.

“During a year when most people don’t know when the deadline is, if the only news you hear is that the A.C.A. was struck down, that is only going to hurt enrollment,” said Joshua Peck, a co-founder of the group Get America Covered and the former chief marketing officer for HealthCare.gov during the Obama administration.

Can I still sign up for coverage?

For the 39 states that use HealthCare.gov, the open enrollment period ended on Saturday.

But 11 states and the District of Columbia operate their own marketplaces. The states are California, Colorado, Connecticut, Idaho, Maryland, Massachusetts, Minnesota, New York, Rhode Island, Vermont and Washington.

The deadlines in those states vary. Some states, such as California, had already planned for deadlines that stretch into January. Connecticut, which had planned to end enrollment on Saturday, extended its deadline until Jan. 15 in response to the Texas ruling. Check your local insurance marketplace for details.