The Common Economic protocols are rules for voluntary interactions based on individual ownership, property rights, functioning free markets and free contracts. You can use them for voluntary interactions as an alternative law system.
These Common Economic Protocols were placed under public domain by Andre Goldman. There is more to it than the public domain part:
We in Parallel Polis Institute of Cryptoanarchy decided to build upon them and facilitate their translation to local languages, so they might be used by more people in their voluntary interactions. We have only used the part that is in public domain (and all derived works here also remain in public domain).
If you have used these Common Economic Protocols in any useful way, please let us know, especially if you have any experience with applying these rules.