Admitted to the Philippine Bar, 2004. He completed his undergraduate studies from the De La Salle University, Manila. He graduated from the Ateneo Law School (Juris Doctor, Second Honors, 2003).
Atty. De Castro he completed his Masters in Law, LLM, from the University of California Berkeley with Certificates of Specialization in IP Law &Technology (including data privacy), and Energy and Clean Technology. Thereafter he obtained his JSD as well in UC Berkeley with specialization in Administrative Law and Regulatory policy.
He was a former Consultant to the Commissioner and Deputy Commissioners of the National Privacy Commission. Prior to that he was an Assistant Secretary in the Department of Justice.
He is also a professor in various law schools including the Ateneo De Manila School of Law.