The first paragraph of the Wikipedia article on common law:
Common law (also known as case law or precedent) is law developed by judges through decisions of courts and similar tribunals that decide individual cases, as opposed to statutes adopted through the legislative process or regulations issued by the executive branch.
From this description, it sounds like there can be no authoritative written laws in common law systems because the only source of law is what has previously happened in court rooms. On the other hand, users on this site seem to agree about the specific details of common law systems without the need for citing cases.
In common law systems, are there specific laws? Are they written down? Or are there only previous court rulings?
The Wikipedia article does refer to laws written by common law legislatures:
For that reason, civil law statutes tend to be somewhat more detailed than statutes written by common law legislatures—but, conversely, that tends to make the statute more difficult to read (the United States tax code is an example).
It also describes New York law regarding contracts as highly detailed, which suggests a written document. Both are these greatly add to my confusion.
My best guess is that in common law systems there are documents which describe precedents that have been set but that these documents have no legal weight themselves. I didn't think there were unwritten laws in the United States though so I'm not at all confident about that guess.