Guilty or not guilty: Using clone metrics to determine open source licensing violations

Unintentionally violating open source software (OSS) licenses by reusing OSS code is a serious problem for both software companies and OSS developers. The simplest intuitive way to identify such reuse is to measure code clonesduplicated code fragmentsbetween a suspected program and an existing OSS program. The question then becomes, what is the lower bound of code clone measurements needed to conclude that the suspected program is guilty (reused code exists) and the upper bound needed to conclude that it is not guilty? In their analysis of 1,225 pairs of OSS products, the authors found 121 with reused code. They experimentally explored the boundaries for three code clone metrics: maximum clone length (MCL), number of clone pairs (NCP), and local product similarity (LSim). Using these metrics, they identified guilty, not guilty, and suspicious programs.