A method and system for detecting plagiarism of software source code is disclosed. In one embodiment, a database exists of program elements that have previously been found to be matching within the source code for two different programs. This embodiment searches the Internet for occurrences of these matching program elements to determine how many times they appear and thus whether they are commonly used or not. The elements and their associated number of hits are placed in a spreadsheet for further observation and manipulation. One of skill in the art will see that this invention also applies to other kinds of text documents.