The influx of neuroscientific data into the criminal justice system has unsettled traditional evidentiary paradigms and posed the critical question of scientific validation for courts. This study, employing a comparative-analytical method, examines and compares the approaches of the legal systems of Iran and the United States in addressing these novel forms of evidence.The findings Indicate that the U.S. judiciary, having shifted from a general acceptance test to a more rigorous and determinate standard, assigns the judge the role of gatekeeper for scientific validity and conditions admissibility on precise methodological indicators such as testability and error rate. By contrast, Iran’s legal system—despite a general receptivity toward scientific evidence and frequent recourse to expert testimony—lacks substantive validation protocols; its reliance on the judge’s unaided assessment (judicial knowledge) without technical underpinning increases the risk of admitting unreliable data or excluding reliable evidence.The article’s original contribution is a locally tailored model to remedy this methodological lacuna. The proposed model requires no new legislation; rather, it activates dormant legal capacities by shifting the burden of technical validation to the Forensic Medicine Organization, standardizing national protocols, and moving from mere conscience-based conviction to reasoned, scientific justification. This approach seeks a responsible balance between harnessing novel technologies and safeguarding the principles of a fair trial.