Clinical research has expanded tremendously in the past few decades and consequently there has been growing interest in the ethical guidelines that are being followed for the protection of human subjects. This review summarizes historical scandals and social responses chronologically from World War II to the Death of Ellen Roche (2001) to emphasize the lessons we must learn from history. International ethical guidelines for studies with human subjects are also briefly described in order to understand the circumstances of clinical research. The tasks and responsibilities of the institutions and investigators in human subject research to preserve the safety and welfare of research subjects are summarized. Next, several debated ethical issues and insights are arranged as controversial topics. This brief review and summary seeks to highlight important arguments and make suggestions to institutional review boards (IRBs) to contribute to the future evolution of ethics in clinical research as we advance forward.