I have been reading the Stanford Encyclopædia article on the subject of laws of nature. The concept of universal laws is relevant to the philosophical problem of induction, and also comes into other metaphysical problems including epistemology and the philosophy of propositions.
It is interesting to try and define what "makes" a universal law. The account which I particularly like explains universal laws in terms of deductive systems, with strength and simplicity being the key characteristics of a universal law.
Another approach employs the philosophical concept of universals to analyse laws of nature. This view was set out by Armstrong as follows:
"Suppose it to be a law that Fs are Gs.F-ness and G-ness are taken to be universals. A certain relation, a relation of non-logical or contingent necessitation, holds between F-ness and G-ness. This state of affairs may be symbolized as‘N(F,G)’"
According to Stanford, the majority of contemporary philosophers are realists about laws; they believe that some reports of what the laws are succeed in describing reality. There are, however, some antirealists who disagree. More on that later.