Name: Rainier Mamangun
Firm Name: Mamangun Law Office
Jurisdiction: Philippines
Practice Area: Family Law

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Professional Biography:

Leaders in Law endorses Rainier Mamangun as our exclusively recommended Family Law expert in the Philippines. If you wish to get in touch with Rainier, please use the contact information provided above.

Atty. Rainier Mamangun’s expertise in family law and domestic relations covers representation and advisory services in annulment, declaration of nullity of marriage, recognition of foreign divorce, child custody, spousal and child support, adoption, and domestic abuse cases, among others. For almost two decades, he has worked on over 200 family law-related cases.

Atty. Rainier R. Mamangun is adept at handling cases in and out of court. His training with the Philippine Department of Foreign Affairs enabled him to hone his diplomatic skills which now prove crucial in his dealings and negotiations with the court and the opposition. His skills at legal drafting and the defense of existing legislation were developed through years of service at the Office for Migrant Workers Affairs and in appearances at Congressional hearings and various inter-agency meetings that dealt with law and policy formulation relating to the welfare of Filipinos overseas. He had defended the constitutionality of the “Migrant Workers’ Act” before the Court of Appeals in coordination with the Office of the Solicitor General.

Prior to establishing the Firm in 2004, Atty. Rainier Mamangun was a lawyer for the Department of Foreign Affairs (DFA) where he worked on labor, civil, and criminal cases involving migrant workers and overseas Filipinos in distress in coordination with Philippine Embassies and Consulates across the globe. He spearheaded various missions to Malaysia, Indonesia, East Timor, Nepal, India and Saudi Arabia to protect the interest of the OFW (Overseas Filipino Worker) ; undertook diplomatic representations with foreign governments in connection with the cases he handled, and appeared before foreign courts such as the Riyadh Grand Court – a rarity for Filipino lawyers. While at the DFA, he was instrumental in the rescue of countless victims of human smuggling and trafficking in Asia, and in saving Filipinos on death row in the Middle East.

In 2003, he was part of the Drafting Committee for the Magna Carta for Seafarers, a bill intended to promote the welfare of millions of Filipino seafarers worldwide. He also briefly worked at the Prosecution Division of the Department of Interior and Local Government (DILG). He was also a Legal Consultant to the National Federation of Labor Unions (NAFLU), then one of the biggest labor federations in the Philippines. In 2013, Atty. Mamangun was the recipient of the Certificate of Selection in the area of Family Law from Legal’s Finest — a premier guide to the world’s leading attorneys based in the United Kingdom. In 2020, Atty. Mamangun was awarded the Certificate of Excellence from Advisory Excellence, a London-based organization which profiles the best legal advisers around the globe, for his outstanding performance in the area of Family Law. In 2021, Atty. Mamangun became one of the select few to be invited to the prestigious Asociacion Europea de Abogados, the largest network of lawyers in the world based in Alicante, Spain

Practice Areas

Bar Admission

Philippine Bar 2001


Member: Fraternal Order of Utopia based in Ateneo Law School


Filipino and English

Firm Description:

Law Office of Atty. Rainier R. Mamangun/Mamangun Law Office is a full-service law firm located in Pasig City, Philippines that offers a wide variety of legal services. Practice areas include family law such as annulment, legal separation, and child concerns, civil cases, criminal litigation, labor law, immigration, corporate law, medical malpractice, real estate and property law, and special projects.

Established in 2004, the firm is led by Rainier R. Mamangun, who has nearly 20 years of legal experience, along with substantial academic and professional qualifications. He has had training with the Philippine Department of Foreign Affairs, which is valuable in current dealings and negotiations, has appeared at Congressional hearings and other meetings, and published papers on several subjects. Mamangun Law Office offers clients a team of lawyers with extensive experience and vast knowledge in a broad range of legal concerns. The firm is dedicated to competence with concern while providing customized services that are focused around clients’ interests.