Is evil a perception or is it something that is objective?
Here's my line of thought on it: "If evil were a perception then the law would be moot to some extent. However, if evil were objective then would that advocate for absolute morality?"
Todd Calder distinguishes between a broad concept of evil which would be any bad state of affairs resulting from either natural causes or moral agents and a narrow concept:
In contrast to the broad concept of evil, the narrow concept of evil picks out only the most morally despicable sorts of actions, characters, events, etc....Since the narrow concept of evil involves moral condemnation, it is appropriately ascribed only to moral agents and their actions. For example, if only human beings are moral agents, then only human beings can perform evil actions. Evil in this narrower sense is more often meant when the term ‘evil’ is used in contemporary moral, political, and legal contexts.
This narrow concept is what the OP appears to be interested in when asking about law and morality:
If evil were a perception then the law would be moot to some extent. However, if evil were objective then would that advocate for absolute morality?
Evil as a perception may be viewed as the position taken by "evil-skeptics". They "believe we should abandon the concept of evil" although they do not generally reject "other moral concepts, such as right, wrong, good, and bad". Calder summarizes their arguments:
Evil-skeptics give three main reasons to abandon the concept of evil: (1) the concept of evil involves unwarranted metaphysical commitments to dark spirits, the supernatural, or the devil; (2) the concept of evil is useless because it lacks explanatory power; and (3) the concept of evil can be harmful or dangerous when used in moral, political, and legal contexts, and so, it should not be used in those contexts, if at all.
Calder identifies Nietzsche as a famous evil-skeptic.
Those arguing for an opposing view, "evil-revivalism", claim the concept of evil usefully focuses attention on the "worst sorts of moral wrongs" to prioritize understanding of them so something can be done about them. They (such as Claudia Card and John Kekes) would claim it may be "more dangerous to ignore evil than to try to understand it".
So a partial answer to the OP's question would be to consider the alternatives provided by evil-skeptics and evil-revivalists. However, that doesn't answer the question about whether accepting evil implies the existence of "absolute morality". This may be something that evil-skeptics and evil-revivalists both want to avoid in trying to avoid supernatural explanations.
One might question whether there are positions besides the evil-skeptic and evil-revivalist positions that also address absolute morality. One may view absolute morality as characterized by moral obligation seen as an obligation to a deity. This deity would give absolute morality its "absolute" characteristic. This deity, however, introduces the supernatural that both evil-skeptics and evil-revivalists want to avoid.
One position that does this indirectly may be that of G. E. M. Anscombe in "Modern Moral Philosophy". She argues with the evil-skeptics that moral obligation necessitates the existence of the supernatural or at least the efforts of modern moral philosophers have not successfully developed "an adequate philosophy of psychology" that removes the need for such a supernatural lawgiver. But she argues against both in claiming their moral positions "are only harmful without" this obligation to a supernatural lawgiver that they both want to avoid.
Adding philosophers such as Anscombe would help cover the concept of absolute morality, viewed as moral obligation, in making a choice between which positions one wants to pursue.
Anscombe, G. E. M. (1958). Modern moral philosophy. Philosophy, 33(124), 1-19. https://www.pitt.edu/~mthompso/readings/mmp.pdf
Calder, Todd, "The Concept of Evil", The Stanford Encyclopedia of Philosophy (Fall 2018 Edition), Edward N. Zalta (ed.), URL = https://plato.stanford.edu/archives/fall2018/entries/concept-evil/.
'Evil', just like the concepts of 'Good' and 'Bad' is a matter of perspective.
Even though it associated with something negative, it does not mean it is always so objectively speaking.
Social Example: If tribe 'A' comes in and occupies all fertile land near tribe 'B' (while not considering them evil or good), from their perspective, they did nothing wrong. They did a good thing to feed their families. From tribe B's perspective, that is an evil deed because it deprives tribe B of their resources.
Now tribe B decides to go and kill the 'evil' occupiers. They will do a good deed to save their food supply. When the attack will happen, tribe 'A' will consider tribe 'B' evil because they are being killed by them.
Moral example: By the same logic, does is justify to kill 1 person to save 1 million ? Is that a good deed (because we saved 1 million) or an evil deed (because we killed one) ? If we consider it good, is it still good if we need to kill 10 for the same reason ? What about 100 ? What about 999 999 ? Where do we draw the line ?
Such a thing cannot be morally objective, it can only be statistically objective, assuming complete information on the subject exists.
Religion example: from current Christian religion's point of view and that of it's followers there's an Evil entity called Satan. But from Satan's and followers point of view it is God who is a Tyrant and Satan the good guy who raised against oppression and tyranny. In a similar manner, some religions will state that the God of the others is evil and that theirs is the good one. Just because one religion has more followers does not make it any better than another.
Political example: During the Soviet era, Americans considered the Soviets 'evil' and Soviets considered Americans 'evil'. This unfortunately continues today between many countries. Just because one side had more countries than another, does not make that side more or less evil.
Let's think it even more interesting: from the Planet's perspective, humans are evil.
As for the law, that has nothing to do with the rest. The law is less and less based on morality, which currently leads to many bad implications, but this is another subject.