Technology presents all manner of new challanges for copyright law… Turnitin is a Web-based tool to allow educators to check the originality of student’s work — it does block text comparisons of papers against its database to find exact or too-close matches. Problem is (from an IP law standpoint) is that students have a copyright in their papers as they are original works. Copy a student’s paper into the database and you may have infringed their rights. Is there a fair use defense?

http://arstechnica.com/news.ars/post/20070330-high-schoolers-turn-in-plagiarism-screeners-for-copyright-infringement.html