When the zombie apocalypse comes, it may be difficult to consult a lawyer or judge about the consequences of killing zombies. Is it murder to kill a zombie?
From a legal standpoint, the most important issue is whether or not they are still considered humans. If not, you'd probably be fine going on a zombie slaughter as long as you don't accidentally kill any uninfected person in the process. If they are considered humans though, you can still kill zombies, but only in self-defense or to defend others. If you start sniping zombies from a rooftop when they present no direct threat to you, you might be in trouble later on.
If there's a question of whether zombies are human, a thorough medical investigation might lay the question to rest. But what about mutants? Are super heroes liable for the damage they cause in the quest for justice, or would they be considered "not human" as well? Or would they be considered humans with disabilities, and therefore covered under the Americans with Disabilities Act? These and other questioned are considered in the post 8 Hilarious Legal Examinations of Unexpected Pop Culture Issues, which covers questionable but completely human perpetrators as well. Link