Wednesday’s oral argument in Dobbs v. Jackson Women’s Health Organization attracted unusually large crowds of demonstrators outside the Supreme Court. The case is a challenge to a Mississippi law that prohibits abortions performed after 15 weeks gestation except where the continued pregnancy creates a health emergency or if there is a “severe fetal abnormality.”

The law conflicts with Supreme Court precedent that limits the state’s ability to protect unborn lives before viability (the point in a pregnancy when the child could live independent of the mother).

The Supreme Court took the case expressly to address the question of whether the Mississippi law is constitutional. But answering that question raises another, more foundational, question: Should the court overrule its two prior decisions that preclude states from limiting or prohibiting abortions of unborn children? This is what Mississippi has asked the court to do.

The first decision – the 1971 ruling in Roe v. Wade (along with a companion case, Doe v. Bolton) – established the de facto principle that the state may not prohibit abortion. It did so based on a formula: During the first three months of pregnancy, abortion could not be regulated; after that point, the state’s interest in defending an unborn life gradually increased in three-month increments, as long as the state allowed for the broadest possible health exception to any abortion regulation.

In the second decision – the 1991 ruling in Planned Parenthood v. Casey – the court revisited Roe and abandoned the trimester approach. The replacement was a rule that the state could not limit abortions before viability, and any regulation could not impose an undue burden on the choice to abort.

The status of Roe and Casey was central to Wednesday’s oral argument before the court.

The usual caveats about oral arguments apply. The justices’ questions may or may not reflect their actual thoughts about how the case could be resolved, and the continuing process of coming to a consensus on an actual opinion may require additional changes. (Interestingly, some of the questions in this argument sounded more like statements, so there may be some justices whose votes we can predict.)

The commentary indicates that observers believe the court will uphold the Mississippi law. Either way, the court will almost surely have to deal with the question of precedent.

Precedent, or stare decisis as it is often referred to in legal discussions, is the principle that when a court has resolved a specific legal question, that resolution should control future cases that raise the same question.

This is clearly a critical principle. The rule of law depends on predictability of outcomes (among other things). Arbitrariness in legal rules is a mark of a totalitarian system. It is important that citizens be able to know whether their actions are in violation of the law. Precedent makes this more likely by allowing those citizens to assume that a settled interpretation of the law will be applied in future cases.

Mere consistency, however, may not always serve the interest of the rule of law. Persistence in a certain interpretation, for example, may short-circuit another key value: the ability of citizens to exercise self-government.

Perhaps more fundamentally, if an interpretation is clearly at odds with the law it purports to apply, it undercuts public confidence in the law. Thus, few would argue that the Supreme Court was wrong in the 1954 decision Brown v. Board of Education to abandon its 58-year-old decision in Plessy v. Ferguson that legal separation by race was constitutional. It was not that the court needed to advance a particular agenda, but that it had to abandon a misinterpretation of the Constitution.

The tension between continuing to apply existing legal rulings and abandoning mistaken interpretations was the most important theme in the oral arguments of Dobbs. The former position was defended as vindicating the expectation of Americans that they can abort a child without state interference. The latter position was exemplified in an exchange between Justice Samuel Alito and Solicitor General Elizabeth Prelogar:

JUSTICE ALITO: Is it your argument that a case can never be overruled simply because it was egregiously wrong?

GENERAL PRELOGAR: I think that at the very least, the state would have to come forward with some kind of materially changed circumstance or some kind of materially new argument, and Mississippi hasn’t done so in this case. It is –

JUSTICE ALITO: Really? So suppose Plessy versus Ferguson was re-argued in 1897, so nothing had changed. Would it not be sufficient to say that was an egregiously wrong decision on the day it was handed down and now it should be overruled?

GENERAL PRELOGAR: It certainly was egregiously wrong on the day that it was handed down, Plessy, but what the Court said in analyzing Plessy to Brown and Casey was that what had become clear is that the factual premise that underlay the decision, this idea that segregation didn’t create a badge of inferiority, had been entirely mistaken.

JUSTICE ALITO: So is your — is it really –

GENERAL PRELOGAR: And, here, the state is not –

JUSTICE ALITO: — is it your answer that we needed all the experience from 1896 to 1954 to realize that Plessy was — was wrongly decided? Would you answer my question? Had it come before the Court in 1897, should it have been overruled or not?

GENERAL PRELOGAR: I think it should have been overruled, but I think that the factual premise was wrong in the moment it was decided, and the Court realized that and clarified that when it overruled in Brown.

By addressing these tectonic questions, the court is likely to do far more than signal what Mississippi must allow in terms of abortion law. It could very well shape the application of the fundamental principles of the rule of law.

In other words, while the Dobbs decision will rule on abortion, it may prove to have momentous civic impacts that range far beyond abortion law. That is something that every American should pay attention to, whatever their policy position on abortion.