Active participation of youth and surrogate decision-makers in providing informed consent and assent for mental health treatment is critical. However, the procedural elements of an informed consent process, particularly for youth in child welfare custody, are not well defined. Given calls for psychotropic medication oversight for youth in child welfare custody, this study proposes a taxonomy for the procedural elements of informed consent policies based upon formal and informal child welfare policies and then examines whether enacted state formal policies across the United States endorsed these elements. A sequential multi-method study design included: (1) semi-structured interviews with key informants (n = 58) primarily from state child welfare agencies to identify a taxonomy of procedural elements for informed consent of psychotropic medications and then (2) a legislative review of the 50 states and D.C. to characterize whether formal policies endorsed each procedural element through February 2022. Key informants reported five procedural elements in policy, including how to: (1) gather social and medical history, (2) prescribe the medication, (3) authorize its use through consent and youth assent, (4) notify relevant stakeholders, and (5) routinely review the consenting decision. Twenty-three states endorsed relevant legislation; however, only two states specified all five procedural elements. Additionally, the content of a procedural element, when included, varied substantively across policies. Further research and expert consensus are needed to set best practices and guide policymakers in setting policies to advance transparency and accountability for informed consent of mental health treatment among youth in child welfare custody.