A HIO, as a business associate, may only use or disclose protected health information (PHI) as authorized by its business associate agreement with the covered entity. See 45 C.F.R. § 164.504(e). The process of de-identifying PHI constitutes a use of PHI. Thus, a HIO may only de-identify PHI it has on behalf of a covered entity to the extent that the business associate agreement authorizes the HIO to do so. However, once PHI is de-identified in accordance with the HIPAA Privacy Rule, it is no longer PHI and, thus, may be used and disclosed by the covered entity or HIO for any purpose (subject to any other applicable laws).