USA: 42 CFR 11 – Interventional means, with respect to a clinical study or a clinical investigation, that participants are assigned prospectively to an intervention or interventions according to a protocol to evaluate the effect of the intervention(s) on biomedical or other health-related outcomes (as per 42 CFR 11.10)
42 CFR 11 (Clinical Trials Registration and Results Information Submission) defines the clinical trial registration requirements for clinicaltrials.gov 