I've recently commented on the ways our legal system protects police officers from civil liability for excessive force and other constitutional violations. See:
Now, the author of the Constitutional Law textbook I used in law school, professor Erwin Chemerinsky, has also chimed in about the topic, in an excellent piece titled "How the Supreme Court Protects Bad Cops." A snippet:
Because it is so difficult to sue government entities, most victims’ only recourse is to sue the officers involved. But here, too, the Supreme Court has created often insurmountable obstacles. The court has held that all government officials sued for monetary damages can raise “immunity” as a defense. Police officers and other law enforcement personnel who commit perjury have absolute immunity and cannot be sued for money, even when it results in the imprisonment of an innocent person.
I highly recommend this piece, not just because it echoes the points I've recently made, but because this topic is important and worth everyone's attention. Judges shield police officers from accountability. Without accountability, there will be no restraint.