Since this ancient thread has been resurrected, I'll provide a quick response to this:
The contract allows us to retain a copy to use, so that other students can scan against previous essays submitted.
That's probably not the clause to which anybody was referring. The
other clause permits them to use anything scanned
"for the purpose of marketing Viper or any associated website of the Company." "Marketing" could include posting parts of those essays as "samples" or even making their full text available on their sites for free download. I don't think anybody had any problem with the specific clause to which "Jennifer" was referring and that she defended above.
Writers who don't plagiarize don't need any kind of plagiarism scanner, simply because everyone (whether he's a professional writer or a student) knows whether the words he's writing come directly from his own mind or from some source. Very experienced writers who have written about various topics many times could accidentally write something very similar to the way they might have expressed a similar idea previously; but nobody needs an online scanner for that: you just do a quick search on your own computer for old projects by topic keywords to make sure that you haven't accidentally written anything much too similar to something you've written before.
Students sometimes have a lot of trouble understanding that paraphrasing or completely rewriting ideas found in source material is still plagiarism if it (meaning the
idea, not the wording) isn't properly cited; but scanners can't help them with that at all, simply because they only recognize identical words and phrases, not the conceptual meaning of those words. Incidentally, they don't recognize contextual meaning, either; and they'll frequently incorrectly "flag" combinations of words identified in material that has absolutely nothing to do with the scanned project. For example, you could write the words "the merciless invasion continued for days" discussing the progress of a virus or other pathogen in a Nursing project about disease and find those words "flagged" because someone once used the exact same combination of words discussing the progress of the Nazis in WW2 Europe.