In the wake of President Trump’s nomination of Judge Brett Kavanaugh to the U.S. Supreme Court, the number-one question on the mind of abortion advocates is what this will mean for Roe v. Wade.

I myself am in the camp that this isn’t a hard question. Barring a surprise change of heart by one of the conservatives already on the Court, Kavanaugh would almost certainly provide the fifth vote to overturn Roe—or, at the very least, to read it and its successors Planned Parenthood v. Casey and Whole Woman’s Health v. Hellerstedt very narrowly to allow almost all restrictions. There really shouldn’t be any doubt about that.

But what exactly will it mean to overturn Roe? At the most extreme, some people worry that a newly emboldened conservative majority would not only overturn Roe but also make abortion illegal throughout the country. As horrible an outcome as that would be, it’s incredibly unlikely.

Here’s a simple way to think about this, one that I always give to my students when covering abortion in class. Consider three different positions regarding the U.S. Constitution and abortion:

1) The Constitution prohibits states from outlawing abortion so it is legal everywhere
2) The Constitution is silent about abortion and lets states do what they want on the issue
3) The Constitution prohibits states from allowing abortion so it is illegal everywhere

Right now, scenario 1 is the still-current legal doctrine. The Court in Roe and its successors has said that abortion is a protected right under the Constitution. Even given the ways Roe has been scaled back, the Court has not changed the basic legal principle that states are prohibited from making abortion illegal.

There is no doubt that abortion is inaccessible for large swaths of people in the United States. Barriers ranging from the Hyde Amendment, to mandatory delays, to targeted restrictions on abortion providers (TRAP laws), to physician-only laws, to clinic picketers, and more, make it very difficult for many people to access abortion. This is especially true for poor women, rural women, and women of color. And when people can’t access an abortion they need, their lives are worse off because of it.

But, even though abortion is very difficult to obtain for an increasing number of people, it is still legal because Roe is the law of the land.

The risk with Judge Kavanaugh joining the Supreme Court is that we move from scenario 1 to scenario 2. If he joins current Court conservatives to overrule Roe, the likely decision would say a) abortion is not a protected right under the Constitution, so therefore b) states can choose to regulate (or not regulate) abortion however they want.

This is how constitutional law works in our country, where there are multiple levels of government: national, state, and local. Generally, state laws can cover whatever topics they want, however they want to do so. For instance, fireworks can be legal in one state, regulated heavily in another, and illegal in a third. Drivers can get their full driver’s license at age 16 in some states and have to wait until 17 in others.

This variance is perfectly acceptable … unless the Constitution addresses the topic. If that is the case, then states have to follow the Constitution or risk being subject to lawsuits. But, if the Constitution does not address the topic, then states can go about their business doing whatever they want.

This has been the position of Supreme Court conservatives since Roe: that the Constitution is silent about abortion, so states are free to do what they want about it. That means that states like New York, California, and Vermont can keep abortion legal even if Roe is overturned. But it also means that states like Texas, Ohio, and Utah can make abortion illegal if they want. And states in the middle can keep abortion legal but excessively regulate it however they want. The Constitution would be irrelevant and states would control the issue. This is the likely scenario if Roe is overruled.

There’s one wrinkle to scenario 2 that is even more worrisome than letting the states do what they want: If states can regulate abortion however they want, so can Congress. In theory, Congress would not be prohibited from passing a federal law that outlaws abortion nationwide. Though this is a possibility, there are several hurdles for such a law, such as how to enforce it in such a large country (think of how difficult it is for the federal government to enforce federal law about drugs in light of all the states legalizing marijuana). Also, conservatives disagree about whether Congress even has the power to regulate local health care, and abortion is health care. Justice Clarence Thomas has suggested this position in past writings.

In the realm of constitutional law, overturning Roe, as extreme as that sounds, is actually the middle position. Which is why there’s a scenario number 3 in the list above. This is the really scary scenario: One in which the Supreme Court overturns Roe and, instead of saying the Constitution is silent on the issue of abortion, says that the Constitution protects fetal life just like any other life. In other words, it would say that under the Constitution, a fetus is a person.

With this interpretation, because the fetus is a person, states would have to outlaw abortion because failing to do so would be denying that person the full protection of the law.

This is an extreme position that would outlaw abortion everywhere, even California and New York. But rest assured, no Supreme Court justice has taken this position. In the minds of even Roe‘s most ardent opponents on the bench, scenario 2 is correct: The Constitution is silent about abortion so states can make it legal, heavily regulated, or illegal.

Justice Scalia made this clear in his dissent in Lawrence v. Texas, the case that overturned Texas’ anti-gay sex law. In a tangent, he talks about what it would mean to overrule Roe. He decries the false assumption “that the consequence of overruling Roe would have been to make abortion unlawful. It would not; it would merely have permitted the States to do so. Many states would unquestionably have declined to prohibit abortion.” Even Justice Scalia, perhaps the most vocal critic of Roe in the Court’s history, did not adopt scenario 3.

So that should set people’s worry aside, with one caveat. Even though scenario 3 is an off-the-wall legal proposition right now, it could become “on the wall” in the near future. Yale law professor Jack Balkin used this terminology to describe what happened with the Affordable Care Act litigation. He said that the theory that Congress could not require someone to purchase health insurance used to be an off-the-wall legal proposition, but through the hard work of dedicated conservative scholars, jurists, and commentators, it moved to “on the wall.” In fact, it was taken so seriously that the Supreme Court upheld Obamacare by a thin 5-4 majority and only because Chief Justice John Roberts adopted an odd theory about Congress’ power to tax.

So while scenario 3 is not supported at all by the law now and would absolutely not be the consequence of overruling Roe, there will no doubt be efforts from the right to move that position into the mainstream of legal thought.

We who support abortion rights must do everything we can to fight this and keep it the wild, unrealistic proposition that it currently is.