Einstein tells us that basic laws of physics should be invariant under change of reference frame. Is the same true of basic laws of morality? What would that mean? I think it would mean that any law of morality which is not invariant under change of reference frame can only be a consequence of a more general moral law that is invariant together with some conditions explaining why, contingently, things are arranged in some particular manner in space-time as to give rise to the non-invariant law. (Similarly, the non-invariant law about dropped objects near the earth moving in the direction of the center of the earth follows from an invariant Einsteinian law together with contingent facts about how matter is distributed in our vicinity.)
Could this abstract observation have any actual consequences? Suppose Georgina believes that when she works unowned land, by natural law the land becomes hers (cf. Locke), and by natural law she gains mineral rights to what is below the surface of the land she has worked. That doesn't seem right. What counts as being "below the surface of the land she has worked" depends on the reference frame. So it can't just be a basic moral law that one gets whatever unowned stuff is below where one worked. A story must be given explaining the lack of invariance. And probably the easiest way to do this is to say that if there is any such acquisition of mineral rights, it comes from a non-invariant positive law. This isn't very interesting, since I assume we knew that there is no natural acquisition of mineral rights.
There could, however, be some slightly more interesting consequences in other areas. For instance, in sexual ethics, it follows that considerations based on the shapes of organs, as well as ones based on inside-outside distinctions (what is in one reference frame a cup that is red on the outside, green on the inside, with juice within is in another reference frame a cup-shaped object that is green on the outside, red on the inside, with juice adhering to the outside due to odd gravitational fields), should not be of basic relevance, absent some further story. Instead, basic moral rules about sexuality should involve reference-frame invariant concepts such as contact, causation, teleology, intention, and consent. This is helpful—it focuses the philosopher's mind on what the morally relevant features of the activities are. (I've used this in a comment to argue that the use of condoms to prevent HIV transmission within a married couple is unacceptable within a Catholic sexual ethics.)