Society as a whole has the same problem defining “proper” behaviour. That is why different countries have different laws and those laws are changed and revised on an ongoing basis.

I think a good starting place is the old “your right ro swing your arm ends at the end of my nose” saying. You can do what you like unless it infringes on the rights and freedoms of others. ( Of course we live in a world where a woman will vehemently claim that 2 guys getting married to each other on the other side of the continent is directly harmful to her personally. )

A bigger challenge would be how to make it self regulating, not requiring an extensive online government.

As stated you would need some secure neutral party that would grant internet ID’s which would be tied to a particular real world person. There would have to be a limited numbe of ID’s per person as well. Perhaps some sort of biometrics combined with an automated double blind encryption scheme?

While no one without a court order should be able to find out who in the real world that ID belongs to, that ID should be attached to all online interactions. ( A benefit is it would cut out “impersonaations”.) Right of the bat it would make it a lot easier for site owners to ban people from their online communities. People would not be able to simply go and make a new handle, or walk to another internet cafe to get around an IP ban.

In real cases of slander, legal proceedings could be taken against the ID, and only if the courts found probable cause would the real world identity need to be revealed. This should limit fishing expeditions while at the same time actually allowing people a chance to go after their harassers. Now, it is usually more trouble than it is worth unless you have unlimited time and deep pockets to try and track down a person stalking, harassing or slandering online. It is just to easy to hide.