A court follows an earlier ruling on the same question under a doctrine called stare decisis, Latin for “let the decision stand”. The judges who wrote the earlier ruling need not sit on the later court, and the parties need not be the same. The rule binds the court itself.
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The doctrine does two separate jobs, and US courts treat them differently. One binds a court to the decisions of the court above it. The other binds a court to its own past decisions.
Why a court follows a ruling it had no part in
The US Court of Appeals for the Armed Forces has laid out the reasoning behind the doctrine in a string of its own rulings. Following precedent makes the law develop in an even, predictable way. It lets people rely on what courts have already decided rather than relitigating settled points. It also protects how trustworthy the courts look, because a rule that changes with each new panel of judges is not a rule a person can plan around.
That reasoning covers “vertical” stare decisis: a lower court’s duty to apply a higher court’s rulings, whether or not the lower court’s own judges would have decided the case the same way. A US Supreme Court decision, once handed down, binds every federal court beneath it on that point of law.
Where the binding force loosens
Stare decisis is strong, but the Armed Forces appellate court has been explicit that it is “not an inexorable command”. A court reviewing its own past rulings, called horizontal stare decisis, can overturn one of them, though only for a “compelling reason”. The court weighs whether the earlier ruling has proved unworkable or poorly reasoned, and whether anything has changed since it was decided. It also weighs what people affected by the rule now expect, and whether overturning it would undermine confidence in the law.
The party asking a court to overrule its own precedent carries what the court calls a “substantial burden of persuasion”, and needs a “special justification” beyond simply preferring a different answer.
What lower courts do instead of overruling
A lower court, unlike a higher one, cannot simply reject a Supreme Court ruling it disagrees with. What some lower courts do instead has become a subject of legal scholarship in its own right. One legal scholar, writing on SCOTUSblog, calls it “narrowing from below”. A court reads an ambiguous Supreme Court precedent as covering less ground than its broadest interpretation, rather than defying it outright.
Narrowing works only where the precedent leaves genuine room to read it either way. Where the Supreme Court’s ruling is clear, a lower court narrowing it is “generally no more legitimate than overruling from below”, in that scholar’s account. Where it is ambiguous, a lower court reading it narrowly is filling a gap the Supreme Court itself left open, which the scholar frames as a kind of delegation to the lower courts.
The same piece points to District of Columbia v. Heller, the Supreme Court’s 2008 ruling that struck down a handgun ban and set out a historical test for gun-control laws. Dissenting, Justice John Paul Stevens feared the ruling might be the first of many gun laws to fall. Few fell, because lower courts read Heller’s test narrowly in case after case that followed.
The starker example is Boumediene v. Bush, in which the Supreme Court held that foreign nationals detained at Guantanamo Bay could challenge their detention through habeas corpus. The US Court of Appeals for the DC Circuit has handled most of the cases that followed, and has read Boumediene’s scope narrowly. Law professor Janet Cooper Alexander argues that reading has “effectively overruled” the decision, according to the same piece. Judge David Tatel and others on that court have pushed back on their colleagues’ reading.
What settles the argument
Whether the DC Circuit’s narrow reading of Boumediene is legitimate turns on a question stare decisis does not answer by itself: what a lower court owes a Supreme Court ruling once its wording runs out. If lower courts exist to predict what the Supreme Court would decide today, narrowing an unclear ruling in that direction is doing the job asked of them. If they exist to treat the Supreme Court’s word as final even where it is unclear, the same narrowing looks like defiance dressed as interpretation.
The doctrine that is meant to make the law predictable turns, at its edges, on a question about the doctrine itself.
