My perspective is that when we consider the "laws" of science, we need to look at them universally. There is a limit to the number of protons that can be held by the strong nuclear force, there is a universal atomic structure and electron arrangement. There is a universality to intermolecular forces that allow for solvent/solute interaction (and water is good for that purpose). Gravity (whether a push or a pull) seems to be universally attractive. Oxygen seems to be universally reactive. So I always contend that there are universal biological "laws" that say that multi-cellular, multi-system organisms will be carbon based. If those organisms step off a cliff, they will fall. If they want to communicate electronically, it will be with some EM frequency that we are familiar with. If they are alive, they will need to respire, digest, metabolize, generate energy...much like humans. Sure, looking for algae under a rock on Mars is a life form, and would be neat to find but I think we are after the intelligent life that can broadcast over great distances. And they will be subject to natural laws, just like we are.