It’s easy to confuse the law, Law, and LAW. Worse, not everyone uses the same capitalization, so when you see someone talking about law, you must think — which law are they talking about? Normally the context makes clear, but Law and LAW frequently are used interchangeably, and that’s not correct.
law
Lowercase law refers to government law — speeding, murder, taxes, etc. Obviously Christians should follow this, as Paul notes in Romans 13.
The only exception would be if a law conflicts or goes against God. For example, a law against prayer. See Daniel 6 for an example.
Law
The Law with one capital normally refers to the Mosaic Law. Not everyone uses this convention, so normally we’ll use the term Mosaic Law to avoid confusion.
Paul in Galatians (3:24–25) informs us Christians aren’t bound by the (Mosaic) Law. The Law came so you would know your sin. That’s all.
So don’t worry, you can eat a ham sandwich.
LAW
It’s less common, but God’s universal LAW can be noted by using all capitals.
The LAW refers to God’s eternal, never changing standards. It existed in the Garden of Eden, under Abraham, Moses, in the New Testament, and today.
For example, murder is wrong. When Cain killed Abel in Genesis 4, it was the LAW he violated, not the law (as no government existed), or the Law (as it was pre-Moses).
Conclusion
Three types of legal rules. Normally how a person uses a term determines which category he speaks of, but not always. In those cases you must do a bit of digging to find out (the Law and LAW can be easily confused).
Christians must follow the law, the LAW, but not the Law. That’s all clear, right?