The Supreme Court recently decided the case of Franchise Tax Board of California v. Hyatt, a fairly interesting case in which a citizen of Nevada brought a lawsuit against a California government entity in a Nevada court. The factual details are not especially important to this post. What matters is how the justices voted to decide the case.
There were two questions. The first, whether an older case called Nevada v. Hall should be overruled, could not be definitively answered because the eight members of the Court tied in their vote. The second, whether the Nevada court applied the correct law when deciding the case, was answered in the negative by six of the eight. Of those six, Justice Samuel Alito merely concurred in the result but did not join the controlling opinion written by Justice Stephen Breyer.
Alito's concurrence is interesting because of its brevity.
When a justice "concurs in the judgment," they agree with the ultimate holding of the case (the end result) but disagree with the reasoning of the majority opinion. Normally, such a concurrence is accompanied by an opinion of its own, explaining exactly why the concurring justice agrees with the holding but departs from his or her colleagues on their approach.
Justice Alito's concurrence in Hyatt has no accompanying opinion. He agreed with the result of the case, disagreed with the majority's reasoning, but was for some reason disinclined to explain why.
Though this is now rare, it is not without precedent. This practice was actually quite prevalent during the reign of Chief Justice Roger Taney between 1836 and 1864, but has declined dramatically since. That said, Justice Alito himself concurred without an opinion in another case just three years ago: Los Angeles County Flood Control District v. Natural Resource Defense Council, Inc. Other examples of silent dissents and concurrences can be found here.
Note that Justice Alito did not do anything wrong in Hyatt. There is no rule requiring Supreme Court justices to write a separate opinion if they concur or dissent in a case. But it is noteworthy when they do not, because they are so rarely reluctant to expound their positions elaborately whenever the opportunity arises.