As detailed in the previous section on abortion, the issue of whether and how the 3L Legal Principle applies to non-human animals is among the most challenging and complex of questions. Here again, there is no obviously correct answer. Because reasonable minds can and do disagree, this issue is also appropriately left to the local communities to decide and implement. That said, it is worth exploring some relevant concepts in considering this issue.

Some reasonable people declare that the 3L Legal Principle does not apply to non-human animals. As such, they conclude the issue of animal rights is properly a moral issue best dealt with in the moral realm. However, it is unclear why the 3L Legal Principle should apply only to humans. It is reasonable to assume many non-human animals, similarly to humans, would prefer not to be aggressed against. Indeed, we can observe non-human animals attempt to resist aggression by struggling in the same way we humans do. We should not be surprised as all non-human animals are conscious, and most can experience pain. They also clearly value their lives and act to sustain them to the best of their ability.

That the non-human animals cannot engage in contracts, bring a lawsuit in court, or even articulate an objection to their treatment does not immediately appear relevant for any particular reason. The human infant can also do none of these things, and we do not argue for the inapplicability of the 3L Legal Principle as applied to human infants. Further, many people accept the 3LP generally for reasons other than a social contract in any event. It is easy to understand how many reasonable people remain unpersuaded that the 3L Legal Principle applies only to humans.

Indeed, when pushed, many advocates for the human-only position soften their views when they realize if the 3L Legal Principle has no applicability to non-human animals, there is no legal basis upon which to object to an immoral dog owner who enjoys torturing his dog. When confronted about torturing his dog, the evil dog owner could simply respond that, like any other piece of personal property he owns, he has an absolute right to do whatever he wants with it. As such, he could torture or even kill his dog, consistent with all aspects of the 3L Legal Principle. Said another way, the cruel dog owner could simply assert the 3L Legal Principle does not apply to non-human animals. Like everyone else, the immoral dog owner is under no obligation to comply with the 3L Moral Principle or any other ideas about what constitutes proper moral conduct. If the 3L Legal Principle does not apply to non-human animals, the evil dog owner is legally entitled to continue to torture or even kill his dog for any reason at all.

Many people who subscribe to the 3LP would not only object to an immoral dog owner’s torture on moral grounds but would also maintain that the law should prohibit it. This position is only possible for the person committed to the 3LP if the evil dog owner violates the 3L Legal Principle when torturing his dog. On the other hand, if the cruel dog owner does not violate the 3L Legal Principle by torturing his dog, the law should allow the dog owner to do whatever he wants to the dog without limitations.

It is easy to understand why a reasonable person could conclude that, at least under some circumstances, the 3L Legal Principle should apply to certain non-human animals. If you accept the 3L Legal Principle ought to apply in some way to the dog, on what basis would you conclude differently as to the cow, pig, chicken, or fish? That you personally love your dog or that your dog may be the cutest animal alive is irrelevant to the question of whether and how the 3L Legal Principle applies to non-human animals.

Where to draw these intricate lines is replete with disagreements even among entirely reasonable people attempting to correctly interpret how the 3L Legal Principle applies in good faith. Reasonable people may conclude differently about the applicability of the 3L Legal Principle to the bonobo monkey or chimpanzee versus a simple worm or even a one-celled non-human living organism. Moreover, the particular underlying reason why a person aggresses against a non-human animal, whether for self-defense, necessary life-saving medical research, life-sustaining food in an extreme emergency, sport in the case of hunting, or simply for the preference of eating it, also seems to reasonably factor into the analysis.

As with the abortion question, relegating these difficult and complex issues to the local community to select from reasonable alternatives will not satisfy everyone. This imperfect solution is the nature of all controversial matters where reasonable minds disagree. On the other hand, imposing a one-size-fits-all law also will not satisfy everyone. Allowing local communities to reasonably experiment with navigating these complicated and complex issues is the best way to resolve them. Moreover, this approach will ultimately reveal the best and most favored constructions of the 3L Legal Principle.

In the final analysis, the low transaction cost of moving to, or doing business with, another local community with a different preferred reasonable construction of how the 3L Legal Principle applies in this area is the most efficient way to determine which laws and rules are best overall. Local communities should be allowed to adopt reasonable interpretations of how the 3L Legal Principle applies in these areas that comport with the reasonable opinions and sensibilities of those who live in that local community. We should respect the reasoned judgments of others in difficult and complex areas such as this one, where reasonable people can and do disagree about how the 3L Legal Principle applies. A diverse, free, and peaceful world can easily tolerate such reasonable differences of opinion on complicated and complex issues.