This paper proposes a method to measure the effectiveness of an ethics program at one of the most prominent pawnshop chains in Mexico, surveying a sample of 519 workers. This research presents a novel approach to the investigation of business ethics by conducting a cluster randomized control trial experiment to assess effectiveness. No evidence of an enhanced understanding of the existing code of ethics from the communication and explanation of the code was apparent. This could indicate an example of a failed ethics program, suggesting the possibility of additional ineffective ethics programs and companies could be wasting resources on them. We demonstrate that it is possible to implement a cluster randomized control trial, which is considered to be the gold standard in impact evaluation. This should lead to the application of more effective methodologies in the field of business ethics, offering a more comprehensive understanding of the effectiveness of ethics programs.