Legal Advice
What is parental and filial privilege in giving testimonies?

Dear PAO,

My aunt recently received a subpoena to testify in a petition filed against her stepdaughter for the deletion of the surname 'Perez' from her certificate of live birth. However, my aunt does not want to testify. From my research, I learned that the court cannot compel my aunt to testify because she is an ascendant of her stepdaughter and may be covered by testimonial privilege. Please enlighten me.