This study examines the regulation of Post-Marketing surveillance by RWE for codifying and supporting decision making by regulatory authorities. RWE describes how a particular drug performs in routine clinical practice while throwing light unto its efficacy and risks compared to that of RCTs. Therefore, instead of criticising and proposing methods for improving RWE, we illustrate how it complements RCTs by revealing variability in treatment and secondary effects that are not observed under controlled conditions in light of recent empirical studies. The report focuses on how RWE can enhance the mechanisms of developing drugs and support idiographic treatments. Data quality and data standardization problems are discussed and more research proposed to advance the methodologies of RWE as well as increase its application.