The quote refers to experience gained in the process of the development of common law.
"Common law, also known as case law or precedent, is law developed by judges through decisions of courts and similar tribunals, as opposed to statutes adopted through the legislative process or regulations issued by the executive branch."
"Common law, also known as case law or precedent, is law developed by judges through decisions of courts and similar tribunals, as opposed to statutes adopted through the legislative process or regulations issued by the executive branch."
[1]http://en.wikipedia.org/wiki/Common_law