This corpus is outdated. Please use its successor PAN-PC-11: https://doi.org/10.5281/zenodo.3250095 The PAN plagiarism corpus 2009 (PAN-PC-09) is a corpus for the evaluation of automatic plagiarism detection algorithms. For research purposes the corpus can be used free of charge. The PAN-PC-09 contains documents in which artificial plagiarism has been inserted automatically. The plagiarism cases have been constructed using a so-called random plagiarist, a computer program which constructs plagiarism according to a number of random variables. The variables include the percentage of plagiarism in the whole corpus, the percentage of plagiarism per document, the length of a single plagiarized section, and the degree of obfuscation per plagiarized section.