In a March Bloomberg poll, three in four Americans said politics will influence the Supreme Court’s decision on the Affordable Care Act. Only one in six said the Court will decide the case solely on the legal merits. The Wall Street Journal‘s Law Blog implied that was a problem, and even quoted retired Justice John Paul Stevens saying the Court has “a wonderful record of trying to decide things on the merits rather than on the basis of our own particular views.”

Justice Stevens is right. The American people are also right. How can both be true?

Appellate lawyers are trained to recognize legal issues, research rules of law, find prior decisions that apply those rules, analyze the facts in the prior decisions, and argue whether and how the facts of the case at hand fit the precedents. Appellate judges read the lawyers’ briefs, listen to their oral arguments, debate the issues, rules, precedents, and facts among themselves, and then write their opinions.

The lawyers are obviously biased in favor of their clients. That’s what advocacy is all about. But judges are supposed to be unbiased. Uh huh.

Judges can try to set aside their biases – political and otherwise – but they’re still human beings. What we experience as “conscious reasoning,” is in fact motivated reasoning. You could call it “self advocacy” – telling ourselves stories to explain why what we experience fits what we believe – and we’re so good at it that we almost always believe our stories. We think we’ve used what Daniel Kahneman calls System 1 to reason carefully, based on facts and neutral principles. Most of the time, however, we’ve just convinced ourselves that it’s okay to agree with System 1’s intuitive, feelings-based decisions. (We’ll discuss this in depth next week in Morning Feature.)

The Justices’ overall legal perspectives – long since embedded in their System 1s – are shaped by their political views. So the American people are right. The Court’s decision will be political … at least in part.

Because there’s an exception to this general pattern of human thinking. When a process requires us to hear different sides of a problem, find a solution, and write out the reasons for our decision – and if we’re not sure who the audience will be and how they’ll react – we get more careful. We still use motivated reasoning, but it’s no longer just about “self advocacy” and convincing ourselves that we’re right. We also want to convince the audience that we’re right.

And the Justices don’t entirely know who their audience will be or how that audience will react. They know their decision will be critiqued by pundits and politicians across the political spectrum in the days and weeks after it is published. But they also know their decision will also become part of our constitutional body of law … read, cited, and debated by legal scholars for decades or even centuries to come. The Justices may have a good idea how today’s critics will respond, but they also have to consider critics who haven’t yet been born.

That’s why Justices are rarely as predictable as we imagine. The presidents who nominate them and the senators who confirm them – none of whom is required to write out reasons – usually settle for “self advocacy” or at most advocacy for an audience they can predict. They make intuitive hunches and tell themselves stories that make their hunches feel reasonable. Then they tell a story they think voters will accept in the next election. They’re very good at that, or they wouldn’t be presidents or senators.

The pundits who try to predict court decisions also settle for “self advocacy” and advocacy for an audience they can predict: their editors. Until recently, most of their work was tomorrow’s fish wrapper, stored only in musty archives to be read later by almost no one. If pundits worried about how future historians would judge their work, we might get better punditry. But deadlines are deadlines and there will be another topic next week and another next month.

In deciding on the Affordable Care Act, the Justices will begin with their System 2 leanings based in part on their political worldviews. But they know that a mere System 2 hunch, hastily ratified by System 1, without questioning their own biases, written down in an archive to be studied by generations of legal scholars not yet born … could destroy their legacies.

No Justice wants to write an opinion that will later be named in the same breath as Dred Scott. So Justice Stevens is also right. The Justices will try to set aside their personal biases and decide the case on its legal merits.

The Affordable Care Act decision will be political. But it will also be historical. That daunting accountability – not to today’s critics, but to history – is why our legal system works so often works so well.


Update: The original version of this story reversed Daniel Kahneman’s System 1 (intuitive reasoning) and System 2 (conscious reasoning).