The US Food and Drug Administration (“FDA”) issued guidance on April 2, 2014 indicating that, because of the US Supreme Court’s decision in US v Windsor, the FDA will now include same-sex couples in its definitions of “spouse” and “family” in FDA regulations. The FDA will recognize same-sex marriages so long as the marriages were validly performed in a state or country that recognizes same-sex marriage, even if the couple now resides in a state that does not recognize same-sex marriages as legitimate. These changed definitions will impact clinical trial regulations, particularly those pertaining to human subject research protections. For example, a same-sex spouse will now be able to provide informed consent on behalf of a subject who is unable to provide informed consent for him or herself. Likewise, same-sex spouses will be able to terminate clinical trial participation on behalf of the spouse. With regard to the financial interests of clinical trial investigators, investigators will now need to disclose a same-sex spouse’s financial interests in order to preserve the integrity of the clinical trial. Additionally, the composition of Institutional Review Boards (“IRBs”) will be impacted; IRBs are required to have at least one member who is not affiliated with the institution and who is not an immediate family member of someone who is affiliated. Under the new definitions, same-sex spouses will be considered immediate family.