Natural law does exist. The difference between natural law and laws of a civilisation? I'll let Feynman hint at it... "Reality must take precedence over public relations, for nature cannot be fooled". To give the context, this was said in relation to the Challenger Shuttle explosion.
I think what GP meant is that it's like the "Scroll direction: natural" option that appeared in OS X system preferences after Apple changed the default scroll behavior to match what happens on mobile devices.
I am guessing that a lot of us "see what they did there".
Natural laws are laws that any rational nation would arrive at... well, naturally. Killing is bad, so is stealing, etc... These are natural laws. Anyone capable of rational thought can see how these things would ultimately be bad for any society.
The others are laws that a nation creates as a result of specifics surrounding itself. Patents are one such example. These exist solely to spur the sharing of ideas by encouraging inventors to document and share them in detail so that they can later be used by society once the patent expires. A temporary monopoly is granted on an idea to encourage this sharing. This way, ideas aren't lost to eternity simply b/c the inventor didn't have the means to fabricate them. This concept is purely a construct of western nations and culture. It's unlikely an isolated society would arrive at a similar construct naturally.
Even forbidding killing isn't a natural law. In many societies it has been legal to kill slaves, animals, foreigners, gays, people who break the artificial laws, etc. So killing is often seen as good for society. No laws of property ownership, right to life, right to freedom, etc are natural. They're just things that some societies, sometimes have decided are worth restricting.
"Rational" isn't objective; it's apparently rational for parts of the US to kill its citizens for committing certain crimes, while most developed nations do not.
