In his opinion for the Court finding that former Attorney General John Ashcroft could not be sued for improper use of the material witness law in the detention of Abudulla al-Kidd, onetime University of Idaho football star, born Lavoni T. Kidd, Justice Scalia wrote :
“Qualified immunity gives government officials breathing room to make reasonable but mistaken judgments about open legal questions, when properly applied it protects all but the plainly incompetent or those who knowingly violate the law.
“Ashcroft deserves neither label.”
In a unanimous decision the Justices did not rule on the Fourth Amendment issue of unreasonable search and seizure, an area that acting Solicitor General Neal Katyal barely touched on during oral arguments in March.
The case is Ashcroft v. al-Kidd.
Lyle Denniston's take on SCOTUSblog is here.