Law abilities have no scientific explanation at all. He would be more fit to Hogwarts than a laboratory. He bears no resemblance to real world surgeons, except on a metaphorical level.
A vaguely scientific explanation, like lighting attacks being the manipulation of electrons, doesn't make it any less magical. You could extend that logic to explain all the spells from Harry Potter. Or even real world pseudo-sciences, like homeopathy: vaccines allow our bodies to produce antibodies by introducing a pathogen, so a small amount of a chemical in the water makes it resistant against said chemical. Of course, the only problem with that logic is that water doesn't work like that. Similarly, electrons don't follow a person's will, they don't discharge without a chemical reaction, and Law own body would not be immune to the electricity generated.