Jules Jones

I understand the point you're making, but I don't think that the things you suggest are always an appropriate test, because they are also exactly what many innocent authors would do if wrongly accused of plagiarism. The evidence in the Edwards case is absolutely cut and dried -- there is extensive word for word likeness, with sources where the dates remove any reason for doubt as to which is the original. But there are less clear-cut cases, where there is broad similarity but no outright copying, or where it's hard to say which came first in manuscript form.

And there *are* authors who will make accusations of plagiarism when the similarity of ideas is very slim, usually in the honest belief they've been plagiarised. There's an example cited by an editor posting in one of the threads (I think at Dear Author, but I'm not going hunting for the thread), of sheep on a hill during an approach to a castle resulting in an accusation of plagiarism. Even with stronger resemblances, coincidences do happen (in sf, it's not uncommon for several authors to be inspired by the same real life incident or science discovery, or even a call for submissions). This is part of what's got a lot of authors frantic about being accused of plagiarism, and saying silly things about are they expected to have footnotes on everything.