WASHINGTON — At his confirmation hearings this month, Judge Brett M. Kavanaugh singled out a 1992 Supreme Court decision, saying it was central to any discussion of the power of precedent. But at the Supreme Court itself, the decision has gone missing.

The decision, Planned Parenthood v. Casey, reaffirmed Roe v. Wade, the 1973 landmark that established a constitutional right to abortion. But Casey did more than that. It included a detailed framework for what courts must consider when they are asked to overrule a precedent.

The Casey decision was “precedent on precedent,” Judge Kavanaugh said at the hearings. He used that phrase a lot.

So you might have thought that the Supreme Court would have discussed or at least cited Casey before overruling major precedents. But in a 5-to-4 decision in June that overturned a 41-year-old decision about public unions, Casey went unmentioned — an absence that offered a glimpse of one possible path to overturning Roe.