Final answer:
The federal regulation that impacts the health care field regarding privacy of a patient's health information is the Health Insurance Portability and Accountability Act (HIPAA).
Step-by-step explanation:
The federal regulation that came into effect on April 14, 2003, impacting the health care field regarding privacy of a patient's health information is the Health Insurance Portability and Accountability Act (HIPAA).
HIPAA sets the standards for the protection of patient information and requires businesses that use health information, such as insurance companies and healthcare providers, to maintain strict confidentiality of patient records. It aims to ensure that patient privacy is maintained and that their health information is secure.