Out of nearly 5,000 reported opinions in the last five years, no one will be surprised that the Sixth Circuit cited its own cases in all but five opinions. But what other circuits does the Sixth Circuit rely on? From the raw numbers, Sixth Circuit judges cite cases from the Second, Seventh, and Ninth Circuits more often than any other circuit. But those numbers are partly driven by the relatively large number of decisions that are decided by, for example, the Ninth Circuit—which, because of its large size, decides nearly twice as many cases as the next largest circuit.
When we control for the number of opinions issued by each court, to get a percentage of opinions that were cited, we can better understand which circuits the Sixth Circuit prefers to cite. In other words, opinions from those circuits are more likely to be cited than opinions from other circuits. Under this metric, opinions from the First, Seventh, Tenth and D.C. Circuits are cited almost three times as often as those from the other circuits. On the other end of the scale are opinions from the Fourth, Fifth, and Eleventh Circuits, which are cited less than half as much as the average. The Ninth Circuit came in last—cited about a third as often as the average of the other circuits.
We also looked at citations in opinions from two distinct areas: products liability and the Lanham Act. Given the focus of products liability on state law, it is no surprise that more than forty percent of Sixth Circuit opinions did not cite another circuit. But in products liability cases, the Seventh Circuit was cited far more often than any other circuit. By contrast, Sixth Circuit panels cited cases from other circuits in eighty percent of its opinions in trademark cases, and cited four or more other circuits in more than forty percent of cases (more than twice the amount than products liability). In those cases under the Lanham Act, cases from the Second and Seventh Circuits had more influence in Sixth Circuit opinions.
This analysis shows what any appellate lawyer knows: it pays to consider which circuit to cite when there is no good decision in your circuit. Each circuit has its own reputation and those reputations vary by area of law.