Qualified immunity for police officers who killed an innocent person during a hostage situation, as the only circuit precedent holding that officials have a duty of care in such a situation was subsequently vacated as moot.
http://media.ca7.uscourts.gov/cgi-bin/rssExec.pl?Submit=Display&Path=Y2018/D07-10/C:17-3380:J:Bauer:aut:T:fnOp:N:2184309:S:0
Since 2011. An occasional commonplacing of the U.S. Circuit Courts of Appeal.
Neither an authoritative statement of the law nor legal advice. Quick work.