Maria started her legal career working in the Office of the Solicitor General, where she defended the constitutionality of laws and state policies particularly in energy, natural resources and government infrastructure projects. Later on, she worked as a Court Attorney in the Supreme Court of the Philippines. As a law lecturer, she taught environmental and natural resources law and administrative law.

Maria Cristina's written works include “Access to Environmental Justice: A Closer Look at the Rules of Procedure for Environmental Cases” and “A Review of Legal Education in the Philippines."

She has also served as a research assistant for Dr. Antonio G.M. La Vina, the Philippines' foremost expert in environmental law, and was part of the research and writing team of the Philippine Judicial Academy of the Supreme Court in the book “Access to Environmental Justice: A Sourcebook on Environmental Rights and Legal Remedies” and “Access to Environmental Justice: A Capacity Assessment on the Pillars of the Justice System.” Prior to earning her Juris Doctor law degree, she was elected as President of the Philippines Chapter of AIESEC, an international youth-run organisation that empowers young leaders to create social impact.