The Food and Drug Administration (FDA) is amending the biologics regulations to permit the Director of the Center for Biologics Evaluation and Research (CBER) or the Director of the Center for Drug Evaluation and Research (CDER), as appropriate, to approve exceptions or alternatives to the regulation for constituent materials. A request for an exception or alternative will be considered for approval when the data submitted in support of such a request establish the safety, purity, and potency of the biological product for the conditions of use, including indication and patient population, for which the applicant is seeking approval. FDA is taking this action due to advances in developing and manufacturing safe, pure, and potent biological products licensed under the Public Health Service Act (the PHS Act) that, in some instances, render the existing constituent materials regulation too prescriptive and unnecessarily restrictive. This rule provides manufacturers of biological products with flexibility, as appropriate, to employ advances in science and technology as they become available, without diminishing public health protections.