Yesterday the United States Supreme Court issues a per curium opinion in a police excessive force 1983 lawsuit out of Arizona. The case was Kisela v. Hughes.
There was no new law created. Essentially, the SCOTUS was beside themselves that the 9th Circuit Court of Appeals got the case so wrong. The SCOTUS reiterated some of the basic tenants of excessive force case law and explained why the officer could not be held liable under the circumstances.
A police officer shot a woman holding a knife. The woman was acting erratically, was within striking distance of a bystander, and ignored orders to drop the weapon. Pretty standard case for qualified immunity. Take the knife out of the equation, and it would be a different situation. Take the bystander out of the equation, and it would also be different (because there was a chain link fence between the officer and the suspect).