JOHN YANG: Abortion will be back at the Supreme Court on Tuesday when justices hear oral arguments in a case challenging FDA rules that make it easier to get Mifepristone, that's the medication that accounts for more than half of all U.S. abortions.

It's an election year reminder of the role executive branch agencies can play in the post roe world.

Just one of the ways the future of reproductive rights could be shaped by who wins the White House this fall.

University of Cal The Fornia Davis Law Professor Mary Ziegler is an expert on the law history and politics of reproductive rights.

Mary, you've written recently that this is the most consequential election for reproductive rights and a half century.

Why do you say that?

MARY ZIEGLER, UC Davis School of Law: Well, I think before this election, what presidential candidates really meant was an opportunity to put justices on the Supreme Court.

And that hasn't changed.

What has changed is that now without Roe v. Wade, a Republican president could do quite a bit to limit access to abortion nationally, including in states that voted to protect abortion rights through ballot initiatives, or that put protections for reproductive rights in place through their legislatures.

So this is the first opportunity we've really had to see what that could look like if we did have a second Trump presidency.

Conversely, I think if you have a Joe Biden presidency, Joe Biden, in some ways, is a sort of firewall against whatever is going to come out of the U.S. Supreme Court.

So if conservatives are able to engineer victories in the Supreme Court in cases like the one that's being argued, this week, a lot of enforcement discretion is vested in the executive branch.

And so one way or another, there's a lot on the line.

JOHN YANG: Let's talk about the ways that a president could influence this, the reproductive rights, sort of the administrative role.

For instance, let's take Mifepristone.

They're fighting about FDA rules.

MARY ZIEGLER: Yeah, I mean, so obviously, if the Supreme Court, for example, was to say that the FDA didn't have the authority to allow telehealth abortions in 2021, or didn't have the authority to lift other restrictions on mifepristone in 2016, the enforcement authority, right, the FDA would be the one to say, if someone was violating the new rules, we're going to impose a civil penalty, or we're going to impose a criminal penalty.

But the discretion about when to do that, or whether to do that at all would depend on who's in the White House, right, who's in that executive branch agency.

And it's reasonable to assume that enforcing mifepristone rules that the Biden administration doesn't agree with wouldn't be a priority for Biden in the same way it might be if Trump is in the White House, and someone is in HHS, who feels very differently about mifepristone, potentially, even though it's an FDA itself, I feel very differently about mifepristone.

JOHN YANG: The Heritage Foundation actually has a whole project of things they want done if President Trump were to win a second term, and one of them is a law governing the U.S. mails.

Tell us a little bit about that.

MARY ZIEGLER: So this law is called the Comstock Act, it was passed really as kind of an obscenity law in 1873.

And it made it a crime to mail a variety of items that its framers believed encourage people to have illicit sex, including originally items for procuring abortion.

Now, there's language in the statute that says items designed, intended or adapted for producing abortion.

So conservative groups are arguing that the Comstock Act makes it a crime to mail any abortion related item.

And they argue as a result, number one, that the FDA doesn't have the authority to allow telehealth abortion.

But number two, that no one really has the authority to perform illegal abortion because every abortion in the United States takes place using some item in the U.S. mail, whether it's a surgical procedure or a medication procedure.

So that question is front and center from Project 2025's mandate for leadership that you mentioned.

And the argument is essentially that President Trump in his second term could start enforcing this statute against blue states on day one against abortion doctors, against drug manufacturers and potentially down the line even against patients because the Comstock Act notably makes it a crime, not just to mail items, but to receive items as well.

JOHN YANG: That law still on the books.

Why is it not being enforced in that way?

MARY ZIEGLER: Well, for a long time, it really hasn't been meaningfully enforced based on the best evidence we have in cases of abortion or contraception released since the 1930s.

It's been enforced in cases involving pornography in the interim years, but not in cases involving abortion and contraception.

And it's hard to say exactly why that is.

I think, in part, we have a lot of Federal Court precedent saying that it's wrong to enforce the Comstock Act in all cases involving abortion, particularly in cases where a patient's health may be implicated, or where a use is lawful.

There also, just for many years was Roe v. Wade.

Right.

So it would argue we've probably been unconstitutional to enforce the Comstock Act in those ways.

So now we have this kind of zombie law that most Americans don't even know is on the books that the Supreme Court in theory could transform into an abortion ban that Americans wouldn't ever vote to enact.

JOHN YANG: Donald Trump has begun talking about a nationwide 15 week ban, ban after 15 weeks of pregnancy on abortion.

Can he do that by himself, or does he need Congress to do that?

MARY ZIEGLER: He would need Congress to do that.

So a lot of the proposals you actually hear President Biden or former President Trump making on the campaign are proposals where they would actually need Congress's approval.

So in the case of President Biden, you know, codifying Roe v. Wade, in the case of President -- former President Trump potentially codifying some kind of 15-week restriction on abortion, and either of those cases, you would need Congress, which is why conservative groups are so much more interested in what the executive branch can do on its own.

JOHN YANG: Well, are there things that an executive or president can do with executive power to either protect abortion rights or expand them?

MARY ZIEGLER: I think it's a little harder for the Biden administration, if there would be a second Biden administration because Biden would have his actions challenged in court.

Those actions would ultimately land before the U.S. Supreme Court and the U.S. Supreme Court, as we know is very conservative, and has been pretty skeptical of the idea of abortion access in the past.

JOHN YANG: Mary Ziegler, University of California Davis, thank you very much.

MARY ZIEGLER: Thanks for having me.