Full Idea
The systematic (Ramsey-Lewis) regularity theory says that a regularity is a law of nature if and only if it appears as a theorem or axiom in that true deductive system which achieves a best combination of simplicity and strength.
Gist of Idea
A regularity is only a law if it is part of a complete system which is simple and strong
Source
Alexander Bird (Philosophy of Science [1998], Ch.1)
Book Reference
Bird,Alexander: 'Philosophy of Science' [UCL Press 2000], p.39
A Reaction
Personally I don't accept the regularity view of laws, but this looks like the best account anyone has come up with. Individual bunches of regularities can't add up to or demonstrate a law, but coherence with all regularities might do it.