For all the attention paid to the legal battle over Texas’s abortion ban, an abortion case before the Supreme Court on Wednesday could have an even more dramatic impact on abortion in the United States.

A conservative Supreme Court is hearing arguments Wednesday about whether Mississippi’s abortion ban at 15 weeks is constitutional. Unlike the case last month on the Texas law, what the justices decide about Mississippi could immediately reshape the abortion landscape, possibly by overturning Roe v. Wade and almost automatically making abortion illegal or very difficult to obtain in about half the country.

Let’s briefly review this case and how it differs from the Texas arguments, and what both could mean for abortion in America. For more, be sure to read coverage by The Washington Post’s Robert Barnes.

The Mississippi case

The law being challenged: Can abortion be banned after 15 weeks? Mississippi passed a law in 2018 trying to do so. Unlike the new Texas law effectively banning abortion after six weeks, it never went into effect. That’s because abortion rights groups challenged it immediately and federal courts agreed it was unconstitutional. It’s taken two years, but the case has wound its way to the Supreme Court, which will hear arguments for and against the law Wednesday.

The argument before the court: Should Mississippi’s 15-week abortion ban be allowed to stand? There is no federal law guaranteeing the right to abortion. But a nearly 50-year-old case from the Supreme Court, known as Roe v. Wade, and subsequent rulings have established legal precedent that abortion should be available until about 24 weeks, which is when a fetus is viable to live outside the womb. From there, it’s up to states to make their own laws. Many Republican-led states have tried to pass laws limiting abortion earlier, but almost all have been struck down by the courts.

“Two generations — spanning almost five decades — have come to depend on the availability of legal abortion, and the right to make this decision has been further cemented as critical to gender equality,” the Center for Reproductive Rights wrote in a brief to the court. That is the abortion rights group behind the lawsuit challenging Mississippi’s ban.

What the justices might decide: We don’t know. But as Barnes points out, it’s notable that the justices even agreed to hear this case. Based on the ruling numbers, it seems clear that Mississippi’s ban is unconstitutional. The Supreme Court usually takes up cases from lower courts when it sees a clear conflict that needs to be resolved. Which raises the question: Could a newly conservative Supreme Court, with three justices installed by President Donald Trump, including Amy Coney Barrett, be ready to knock down current abortion rights? She and other Trump-appointed justices — Neil M. Gorsuch and Brett M. Kavanaugh — have indicated openness to curbing abortion rights.

Mississippi is feeling pretty bullish. State officials are asking the court not just to uphold their law but to knock down Roe v. Wade entirely. That plus other legal rulings protecting abortions, Mississippi wrote in a brief to the court, represent “unprincipled decisions that have damaged the democratic process, poisoned our national discourse, plagued the law — and, in doing so, harmed this Court.”

The abortion issue is one of the longest-standing battles in modern American politics, and conservatives have every reason to feel they’re within arm’s reach of winning it.

The Texas case

The law being challenged: This fall, Texas banned abortions at around six weeks, before many people know they’re pregnant. Lawmakers anticipated the law might be struck down by the courts, because a six-week fetus is nowhere near viable on its own. So they designed it specifically to evade the courts. It enables regular people to enforce the ban by suing anyone who aids an abortion. The court system is set up to tell state officials to stop enforcing a law, not regular people.

The argument before the court: It’s much narrower than the Mississippi case. The justices decided to let the law stand despite an emergency appeal from abortion rights providers, a signal to many watchers that they are willing to knock down abortion rights to some degree. Then the justices heard arguments this month about whether abortion rights providers and the Biden administration can sue to try to challenge the law. In essence, it’s a legal procedural question, not a question of whether Roe v. Wade should stand.

What the justices might decide: We don’t know; they haven’t shared their opinion yet. But during arguments, even conservative justices seemed amenable to allowing challenges to the Texas law to go forward, Barnes reported. “There’s a loophole that’s been exploited here or used here,” Kavanaugh said.

What happens next: We may not know what the justices think about these cases until next summer, just a few months before the congressional midterm elections. (Results are mixed about how Supreme Court battles motivate each side’s base.) If the court upholds parts of either law, expect abortion rights to topple across the nation. At least a dozen states have trigger laws that would automatically end most abortions. Some liberal states have laws in place that would protect rights.

At the congressional level, House Democrats voted to protect abortion rights under federal law this fall, but Republicans in the Senate would never let that through. It would take Democrats keeping their tenuous hold on power in Congress and agreeing to get rid of the filibuster to reinstate abortion rights nationally.