Contract cheating -- outsourcing student assignments for a fee -- presents a growing threat to the integrity of higher education. As contract cheating is based on students purchasing assignments that are original (albeit not created by the student), traditional plagiarism detection tools remain insufficient to detect contract cheating. Part of the problem is that proving contract cheating is difficult. As a result, instructors may find it hard to prosecute students (i.e. put them through university academic dishonesty proceedings). To help address the problem, this conceptual paper builds upon extant scholarship on contract cheating and argues that a novel evidence-based approach is needed. Such an approach should allow instructors to detect and prosecute cases of contract cheating effectively and efficiently. The paper then presents an outline of such an approach and calls it the "Doping Test" approach as it mimics some aspects of doping testing in professional sport.