Eve Online recently changed its Terms of Service and made pretending to be another player a bannable offence. Naturally, this being Eve, there is an uproar over the issue.
This issue is very interesting. Once you start examining the situation in detail, it leads to a lot of different places and different ideas.
One thing this illustrates is that there is a real "asymmetry of justice" in online games. The bad player can scam you, but you cannot punish her. In the real world, a scammer can be caught and lose their liberty or life. But in most online games, players cannot effectively punish other players. They cannot jail them, they cannot permanently kill them.
Even ostracism is very hard to pull off. As a simple example, you cannot prevent a player in Eve from trading with you, because the markets are implemented with an in-game system.
Of course, players punishing other players might lead to more griefing, which is why everyone stays away from it. But this leaves the game company as the only entity capable of punishment, capable of enforcing laws.
In a sandbox game, the game company should enforce the "laws of nature" of the world. How the world works, the nuts and bolts of physics. Ideally they would not enforce the "laws of man", leaving that up to the players. But other than A Tale In The Desert, no game has made that distinction. And even ATITD still had the game company be the enforcer of the laws.
The other problem, of course, is that of alts. In a way, alts are not really different characters. They are masks or disguises that a single character wears. And these masks are virtually impenetrable to other players. Once again, only the game company is capable of penetrating the disguise to the character underneath. And the mask can be discarded and thrown away if necessary.
Again, that makes it very hard for players to enforce laws or punish those who break them.
Eve takes pride in it's "Wild West, anything goes" atmosphere. But another way of looking at it is that Eve deliberately coddles the outlaws, denying the sheriffs the necessary tools to impose law and order.