GEOFF BENNETT: It's the latest flash point in the fight over abortion rights, dueling decisions.

In Texas, a federal judge is halting the FDA's more-than-20-year-old approval of the drug mifepristone, one of the main medications used to provide abortions.

But less than an hour later, a conflicting court ruling out of Washington state.

A judge there ordered the federal government to protect access to the drug in 17 Democratic-led states and the District of Columbia.

The two decisions are the most significant abortion ruling since the U.S. Supreme Court overturned Roe v. Wade last summer.

For more on the legal path ahead, are joined by Mary Ziegler.

She's a law professor at the University of California, Davis.

Her most recent book "Roe: The History of a National Obsession."

Thank you for being with us.

And these competing orders signal that this issue is almost certainly bound for the U.S. Supreme Court.

We could be waiting for another potentially seismic ruling on abortion.

Walk us through the next steps.

What's -- what's the timeline?

MARY ZIEGLER, University of California, Davis: Well, we're seeing -- the government has sought a stay of the court's ruling and also tried to buy more time, essentially, before anything happens for the parties to more fully air this out before there is a decision whether the approval of mifepristone will be suspended.

Of course, the FDA is appealing on the merits the conclusions that Judge Kacsmaryk drew in the Texas ruling and is seeking clarification from the Washington court about what exactly the FDA is being asked to do, given Judge Kacsmaryk's ruling.

So there are a lot of filings being fired off here and there.

We think, ultimately, that we're going to need to get clarity both from the Fifth Circuit Court of Appeals and ultimately from the U.S. Supreme Court, given that the FDA is being given these conflicting instructions.

GEOFF BENNETT: Mary, you wrote a piece for "The Atlantic" recently and.

You said this unprecedented ruling by Judge Kacsmaryk of Texas is not just a bid to block access to abortion pills.

You wrote -- quote -- "It's an open invitation to anti-abortion rights groups to use the Comstock Act, a law passed 150 years ago and rarely enforced in the past century."

Tell us more about how this law from the 1870s has to do with access to abortion pills.

MARY ZIEGLER: Yes, this is a strategy we have seen crop up in lots of different parts of the anti-abortion movement recently, but, in this suit, the Alliance Defending Freedom and their client, the Alliance For Hippocratic Medicine, essentially argued that this 1873 law, the Comstock Act, makes it a federal climb to mail mifepristone.

And the language of the act is pretty broad.

It covers not just drugs intended for an abortion, but drugs adopted for abortion, which, as you can imagine, could be extraordinarily broad.

And Judge Kacsmaryk said the text means what it says, it says what it means.

We don't need to worry about the fact that federal courts have not interpreted the Comstock Act this way since the 1920s.

So, going forward, if the language is that broad, we're likely to see challenges to other abortion drugs and devices as well.

GEOFF BENNETT: In the meantime, what does this mean for states where abortion is still legal, or states like Washington, Massachusetts, California, where officials have said that they're now stockpiling mifepristone?

MARY ZIEGLER: Yes, I mean, we're likely to see more legal uncertainty there.

I mean, obviously, in the short term, we have this order from Judge Rice essentially telling the FDA to preserve access to mifepristone in those locations.

But Judge Kacsmaryk's ruling has signaled that there are strategies available to the anti-abortion movement that could block access to mifepristone in blue states, as well as red and purple states.

And so you're seeing preliminary steps by blue states to really to stockpile mifepristone and take other steps.

A lot here is also going to depend on how the FDA ultimately uses its discretion and how much it goes after mifepristone, if that's ultimately the conclusion that the U.S. Supreme Court reaches in terms of whether it was properly approved or whether it's subject to the Comstock Act.

GEOFF BENNETT: Well, let's talk more about that because the FDA doesn't target every unapproved drug on the market.

And there are some Democrats, there's some legal scholars who say that the administration should basically ignore the Texas ruling and that, given the conflicting order from Washington state, the FDA should use its discretion and not go after manufacturers that continue to provide mifepristone.

Is that a viable option?

Is there any precedent for that sort of thing?

MARY ZIEGLER: Yes, I mean, I think the best analogy, often, if you think of prosecutors, for example, we're familiar with the idea of prosecutorial discretion, essentially, the idea being that, if you have a bunch of people violating the law, you only have so much time and so many resources.

And so you allocate those resources toward what you think are the biggest threats.

And I think the FDA would be within its rights to say, look, we don't think mifepristone is a dangerous drug.

We think it's safe and effective.

And so while it's unapproved, we're not going to prioritize violations involving mifepristone in light of that.

And that I think that discretion is used by the FDA somewhat often.

I think ignoring the court is a very different thing.

And I think Democrats advising that are on dangerous territory.

Discretion is different, because the FDA like a lot of other enforcement bodies, uses discretion all the time.

GEOFF BENNETT: This Texas case has drawn scrutiny because of where and how it was filed.

When anti-abortion groups wanted to challenge the FDA's approval, they didn't file the lawsuit in Maryland, where the FDA is based.

They didn't file a lawsuit in any of the states where abortion is still legal.

They filed it in Amarillo, Texas, because they knew that it would end up before this particular judge.

This idea of forum shopping or, I guess, in this case, judge shopping, how common is that?

And is this a tactic that we should expect to see more of?

MARY ZIEGLER: Yes, I mean, forum shopping has been around for a long time and isn't unusual at all.

But I think what makes this judge shopping more unusual is the way Texas has organized its district courts.

For example, if you filed a lawsuit in Dallas, you wouldn't know which judge you were going to get.

So you may think you would have a more favorable outcome in Dallas than in Maryland.

But, beyond that, you couldn't predict exactly who would be hearing your case.

The only district judge presiding in Amarillo is Judge Kacsmaryk.

And so that meant that this suit was filed specifically with him in mind, because there was a belief, probably correctly, that he will be the most sympathetic federal judge in the country at the district level to these arguments.

And I think that's a little worrisome just because you have not only forum shopping, but suits that are resulting in nationwide injunctions being filed before judges who are believed to be political or to have certain biases that will slant them one way or another.

And I don't think that's good for the system.

I also don't think it's good for the perceived legitimacy of the courts, which has also taken a hit in recent months.

GEOFF BENNETT: Mary Ziegler is a law professor at the University of California, Davis.

Mary, thanks so much for your time and for your insights.

MARY ZIEGLER: Thanks for having me.