Today, the Supreme Court zigged in another direction on an issue where it has both zigged and zagged, and that is the order of answering the two questions that make up the question of qualified immunity. One question is, does the plaintiff have a claim under the Constitution? The other question is, did the defendant violate the clearly-established constitutional rights of the plaintiff, of which a reasonable government official in his or her position should have known?
If the courts have to answer the merits question first, then a bunch of advisory opinions about constitutional issues get generated. If the courts can answer the "clearly-established" question first, then the law never gets any clearer, and more defendants win.
The conclusion in Pearson v. Callahan is that the courts can go whichever way works best.
You can click here to see some of what I have written in the past on qualified immunity - one of my favorite topics, and the subject of an article I wrote for the VADA some years ago.