Doubtless time travel will raise a host of legal difficulties, e.g., should a time traveler who punches his younger self (or vice versa) be charged with assault? Should the time traveler who murders someone and then flees into the past for sanctuary be tried in the past for his crime committed in the future? If he marries in the past can he be tried for bigamy even though his other wife will not be born for almost 5000 years? Etc., etc. I leave such questions for lawyers and writers of ethics textbooks to solve.

— Larry Dwyer, “Time Travel and Some Alleged Logical Asymmetries Between Past and Future,” Canadian Journal of Philosophy 8:1 (March 1978), 15-38