I'm not sure what's intended by "appropriate" there-- it might not be so much a claim about the law as a claim that it's a name the person wants to use and you shouldn't argue with them about it.
Even then, impersonation is an issue..
Sometimes a user puts something in a "name" field that they do not actually intend to be used to identify themselves.
They may be trying to get that string displayed to other users in a highlighted fashion. If someone puts "Wal-Mart Sucks" in the name field on a blog comment, it isn't because they seriously want to be identified by the surname of Sucks. They're just saying that Wal-Mart sucks, in a dramatic way.
They may be trying to break the system in one way or another. If someone puts their name as "Robert'; drop table students; --" then depending on the social and technical context they might be giving themselves a clever alias; or they might be trying to attack the database.
There are some long lists of false beliefs that programmers hold. isn't because programmers are especially likely to be more wrong than anyone else, it's just that programming offers a better opportunity than most people get to find out how incomplete their model of the world is.
I'm posting about this here, not just because this information has a decent chance of being both entertaining and useful, but because LWers try to figure things out from relatively simple principles-- who knows what simplifying assumptions might be tripping us up?
The classic (and I think the first) was about names. There have been a few more lists created since then.
Time. And time zones. Crowd-sourced time errors.
Addresses. Possibly more about addresses. I haven't compared the lists.
Gender. This is so short I assume it's seriously incomplete.
Networks. Weirdly, there is no list of falsehoods programmers believe about html (or at least a fast search didn't turn anything up). Don't trust the words in the url.
Distributed computing Build systems.
Poem about character conversion.
I got started on the subject because of this about testing your code, which was posted by Andrew Ducker.