The objective of this study was to conduct a review of the benefits and adverse effects of cannabis (or marijuana) legalization in various states across the US. The current study offers a preliminary evaluation of the problems concerning marijuana legalization in several states, with the primary goal being the assessment of the impact of laws and policies governing the legalization and use of marijuana for medical purposes. A comprehensive search on cannabis and its derivatives was performed using multiple resource databases: PubMed, MEDLINE, Embase, PsycINFO, CENTRAL (Cochrane Controlled Register of Trials), government web sources, and the Department of Public Health databases. A total of 47 reports that evaluated the effects of cannabis legalization were included in this review. All review stages were conducted independently by two reviewers. Data were extracted in standardized tables by one reviewer and adjusted by a second, which were verified by the third author. We examined the use of cannabis before and after the changes in policy and the impact of marijuana legalization on traffic safety, behavior and educational achievement in adolescents, public health, tax revenues, criminal justice expenditures, and financial outcomes. We analyzed the effects and consequences of marijuana use in states that have or have not legalized marijuana. This report also includes the responsiveness of the people in states where marijuana is legalized and its value in the healthcare system. Our study highlights the existing limitations of reviews that probe the effect of decriminalizing marijuana in some states of the country. Our analysis shows that detailed and precise evaluation of policy dynamics must be conducted, taking into account the heterogeneity in population sub-groups and policies. Accordingly, in states where marijuana is used for its medicinal value and recreational purposes, people have different views on the legalization of marijuana. The complete effect of legalizing and commercializing marijuana on consumers' mental health and their educational outcomes is expected to take a longer duration prior to its achievement; unfortunately, fewer merits are anticipated. Most of the reports evaluated in this article proved to be marred with inconsistencies. Many of the stated claims did not pass a methodical evaluation. Going forward, additional data from available sources will lead to stronger conclusions. We weighed the pros and cons of marijuana legalization. However, we are certain that consumers can make better decisions by weighing each opinion by its reliability and safety.