ABSTRACT
There are more than 25 software systems in existence that are marketed as plagiarism detection or plagiarism prevention software systems. Some are available free of charge and others cost a yearly fee per student. It would be more correct to call such systems text-matching tools, as they are not actually able to detect plagiarism, a concept which encompasses a wide range of notions that include translations and non-referenced paraphrases or even aspects of intent. In order to understand why software cannot even find all exact text matches, it is necessary to first understand two major concerns that arise when using any such software system: false positives; false negatives. A recent decision by the German Federal Administrative Court has determined that universities are within their rights to rescind a doctorate even after many years have passed and that they alone determine the criteria for doing so.
