Does a principal have an ethical responsibility to inform an unaware third party that an apparent (ostensible) agent does not in fact have authority to act on the principal’s behalf?

In 1990, Desert Hospital in California established a comprehensive perinatal services program (CPSP) to provide obstetrical care to women who were uninsured (perinatal is often defined as relating to the period from about the twenty-eighth week of pregnancy to around one month after birth). The CPSP was set up in an office suite across from the hospital and named “Desert Hospital Outpatient Maternity Services Clinic.” The hospital contracted with a corporation controlled by Dr. Morton Gubin, which employed Dr. Masami Ogata, to provide obstetrical services. In January 1994, Jackie Shahan went to the hospital’s emergency room because of cramping and other symptoms. The emergency room physician told Shahan that she was pregnant and referred her to the clinic.