De Guzman San Diego Mejia & Hernandez Law Offices (GSMH Law)

Member of ASEAN Legal Alliance


16th Floor, Trident Tower Building,
312 Senator Gil Puyat Avenue,
Salcedo Village, Makati City
Philippines, 1200

TELEPHONE:  +632 5110908 / +632 8050002 / +632 5110925

FAX: +632 8776006



De Guzman San Diego Mejia & Hernandez Law Offices (GSMH Law) is a full-service law firm that readily and efficiently attends to the legal needs and requirements of clients with varied demands.

The Firm’s highly experienced team of legal practitioners, combined with its legal resources, allows it to provide effective legal service to local and multi-national corporations as well as major business enterprises. The Firm likewise caters to small and medium-sized businesses, as well as individuals.


GSMH Law was founded in 2008 by four dynamic and passionate lawyers with a single aim in mind: to provide services at par with institutional law firms through a client-oriented practice. The firm greatly values its relationship with clients and thus puts significant focus in the personalized services it renders. Every client is unique, each client is important.
Drawing from the work ethic and professional experience they gathered as colleagues in one of the top law firms in the Philippines, GSMH Law is committed to providing efficient and effective legal advice to its clients. The partners’ and associates’ extensive and diverse expertise in substantive, procedural, and administrative law guarantees that its current and prospective clients will be given paramount legal advice and proper direction in resolving their legal issues and concerns.
Since its inauguration in February 2008, clients who retained GSMH Law continue to receive personalized and quality legal assistance under fee arrangements that are fair and practicable for both parties. GSMH Law regards its roster of clients with utmost respect and importance, and welcomes all prospective clients with the same courtesy.

GSMH Law’s legal team includes highly competent and well-trained paralegals and staff who are dedicated to extending assistance to the lawyers, ensuring adequate and cost-effective service. 





Administrative Litigation – defense and prosecution of administrative charges before administrative tribunals.
Admiralty Claims – actions involving seafarer’s claims, loss or damage to cargo, collisions, salvage, towage, marine pollution, ship arrests and other maritime incidents.
Alternative Dispute Resolution – mediation, conciliation, informal negotiations for amicable settlements.
Appellate Practice – appeals before the Regional Trial Court, the Court of Tax Appeals, the Court of Appeals, and the Supreme Court.
Banking – administrative actions before the Bangko Sentral ng Pilipinas, violations of bank loan agreements, foreclosure of bank mortgages, other administrative cases involving financial institutions.
Civil Cases – actions for specific performance, rescission, annulment, restitution, damages, quasi-delicts and torts.
Corporate Litigation – intra-corporate disputes, proxy issues, corporate takeovers, enforcement of stockholder rights, derivative suits, invalidation of transfers of shares, corporate rehabilitation, insolvency proceedings.
Criminal Litigation – prosecution of criminal complaints as private prosecutors or defense against criminal complaints.
Family Law – adoption, annulment, declaration of nullity, custody, legal separation, separation of property, succession, application for protective orders.
Insurance Claims – non-life insurance claims, enforcement of health insurance claims and handling of other cases before the Insurance Commission.
Intellectual Property Litigation – patent infringement, trademark infringement, copyright infringement, search and seizure operations.
Product Liability – claims for damages for defective products or goods and consumer complaints before the Department of Trade and Industry.
Property Disputes – cancellation of titles, recovery of possession, encroachment of property, abatement of nuisance, ejectment.
GSMH Law recognizes the importance of this field of law in business enterprises. Hence, the firm advises its clients not only on how to manage existing labor problems but also on how to prevent these labor issues from arising.
Labor Advisory - conducting audit of human resource related practices, drafting of employment contracts and codes of conduct/employee regulations, drafting policies for retirement programs, drafting forms used by human resource departments, compliance with pertinent laws and regulations, assisting in the design and implementation of manpower reduction programs, assistance in collective bargaining negotiations, assistance in closure of businesses, advising on the human resource aspect of corporate acquisitions, mergers or spin-offs, advising on payroll management, managing certification elections, and assistance in drafting corporate codes of conduct.
Labor Advocacy – termination disputes, money claims, labor-related civil and criminal cases, negotiations with labor unions, collective bargaining negotiations, strikes and lockouts, cases for unfair labor practices, Social Security System cases, grievance arbitration.


GSMH Law has a highly competent team adept in handling admiralty issues such as ship registration, ship sale and mortgage, collisions, salvage, ship arrests, cargo claims, and seafarer’s claims. The Firm also has partnerships with several medical doctors who specialize in the practice of maritime medicine to assist in the technical aspect of seafarers’ death or disability claims.

The firm advises local and international clients on the regulatory framework imposed by the Monetary Board and the Bangko Sentral ng Pilipinas governing transactions involving bank deposits, investments, loans, derivatives and trusts, and ensure that their commercial transactions, corporate records and practices are in line with applicable regulations.

GSMH Law has developed its mining practice to address the legal demands of emerging as well as existing mining companies. In a short period of time, the Firm has gained legal expertise in mining law and has successfully addressed its clients’ concerns in this field.

Corporate Concerns - the Firm renders assistance on various commercial concerns. This includes advising on the Philippine investment climate, business structuring, registration and accreditation with appropriate government offices, commercial negotiations, the documentation of financing and securitization transactions, and monitoring compliance with contractual commitments. GSMH Law also performs a wide array of corporate legal work for its clients namely: incorporation and establishment of subsidiaries and branch offices; establishment of foundations and non-stock, non-profit corporations; accreditation and registration with relevant government agencies (i.e. POEA, BSP, DENR, MARINA); closure and winding down of operations; due diligence; contract drafting, review and negotiations; securing permits (from local government units and pertinent administrative agencies and bodies); corporate planning and structuring; mergers and acquisitions.
Business Services – GSMH Law assists clients in establishing their businesses from the ground up, advising on the business structure best-suited to the client’s business goals, taking into consideration investment and nationality requirements, equity restrictions and tax issues, among others. The firm’s services include the preparation of the constitutive documents of the proposed company, registration with the Securities and Exchange Commission, the Bureau of Internal Revenue, Social Security System and other agencies. We also assist client in obtaining business and tax permits, and municipal licenses and the preparation and filing of required regular reports with the appropriate government agencies.
Real Estate Solutions – The firm helps its clients achieve the most value out of their real estate holdings and guide them through the various regulations governing the use, possession and development of real property, including the legal regime governing special economic zones. The lawyers of GSMH Law have expertise in public and private infrastructure projects and developments, construction of condominiums and subdivisions, and commercial leases.
E-Commerce & Technology – GSMH Law advises clients on the regulatory framework imposed by relevant government agencies, such as the National Telecommunications Commission, governing the set-up, operation and business transactions of telecommunications companies, and ensure that their commercial records, transactions and service contracts are in line with such regulations.

The Firm has advised and assisted some of the largest insurance providers in the country on policy coverage, liability and enforcement issues. The GSMH Law team guides its clients through the regulatory regime imposed by the Philippine Insurance Commission. On the other end of the spectrum, the firm advises corporate clients on insurance issues affecting construction and infrastructure projects, contractor’s liabilities, directors’ and officers’ liabilities, and insurance against terrorism. GSMH Law has extensive experience in insurance disputes and litigation.

GSMH Law assists clients in understanding the regulatory regime governing Philippine trade and customs regulation, by advising on the importation process, valuation and customs tax and duties.
GSMH has a solid background in intellectual property law.
Intellectual Property Administration – registration of trademarks, trade names and service marks, maintenance of marks, registration of utility models and industrial designs, deposit of copyright, registration of trademark use agreements, assignment of marks.
Trademark Enforcement – developing and managing trademark protection programs


Our Partners


Managing Partner 

Ateneo de Manila University Law School 1998, Juris Doctor
University of Wales, Cardiff Law School 2003, Master’s Degree in Admiralty Law

Mr. de Guzman has extensive experience in commercial, civil, and criminal litigation. He specializes in the following fields of practice among others: corporate law, intellectual property, admiralty law, and contract enforcement.
He also advises clients on corporate assets management, formation of joint ventures and partnerships, compliance with local and national government regulations, immigration requirements of foreign expatriates, estate planning, and labor-management relations. Mr. de Guzman is equally competent in arbitration before domestic and international arbitral bodies.
Apart from practicing law, Mr. de Guzman owns several businesses. This provides him with the correct mind-set on how to avoid potential legal problems in the corporate sphere. This background in business management likewise helps in the resolution of legal issues affecting corporations and individuals. His mastery of entrepreneurial goals enables him to structure legally viable and acceptable ventures or partnerships involving domestic or foreign capital. 



Founding Partner

University of the Philippines College of Law 2002
Bachelor of Laws

​Mr. Mejia has been assisting domestic and foreign clients on a range of legal concerns.
He began his career as a litigation practitioner. His formal litigation practice has included representation of clients at all levels of the Philippine court system and at administrative agency proceedings.His exposure to various commercial disputes has allowed him to develop a strong practice in various areas of commercial  law.
He has handled structuring, compliance and setting of various types of business entities appropriate and desirable for the clients' respective objectives and needs.   He has assisted clients in securing tax incentives from various agencies. 
Mr. Mejia also has an extensive experience on mergers and acquisitions involving foreign principals, mostly based in Japan, China, India and Singapore.As lead counsel for these projects, Mr. Mejia oversaw the due diligence reviews prior to acquisition and led the preparation and negotiation of the transaction documents and the closing of the transaction
He has advised clients in formulating and memorializing company/employee policies and in the enforcement of these policies.  He also supported clients and their officers and staff with their immigration requirements.
He has assisted clients with their concerns on intellectual property protection and management through registration and advocacy before administrative and judicial tribunals through civil and criminal proceedings.
He works with clients with their regular corporate housekeeping concerns and in dealing with audits from various government agencies, such as the Department of Labor and Employment and the Bureau of Internal Revenue.

Founding Partner 


University of the Philippines College of Law 2000
Bachelor of Laws

Mr. San Diego has significant experience in representing individual and corporate clients that are engaged in diverse industries such as manufacturing, insurance, financial services, construction and infrastructure, restaurant management, retail, pharmaceuticals, computer and electronics technology, real estate development, as well as emergent industries of knowledge and business process outsourcing.
He has established an expertise in complex litigation as well as counselling on contract negotiation and documentation. His principal areas of expert consultation include loan and financial arrangements, property acquisitions and development, and Philippine investment incentives.
Mr. San Diego specializes in business and commercial litigation and has represented clients in various stages thereof. He has given lectures on various legal subjects for Management Systems International (MSI), a global international development firm providing specialized short- and long-term technical assistance.  He was also a consultant for the Millennium Challenge Account- Philippines Threshold Plan Technical Assistance Project (MCA-PTP TAP) and has given lectures on various legal subjects for Management Systems International (MSI), a global international development firm providing specialized short- and long-term technical assistance.


Founding Partner


University of the Philippines College of Law 2002
Bachelor of Laws

​Mr. Hernandez specializes in intra-corporate disputes and handles several high-profile litigation involving top corporations in the country, complex civil, commercial and criminal litigation, arbitration, intellectual property enforcement, and appellate practice.  He has extensive experience and exposure before administrative and quasi-judicial bodies and in all levels of Philippine courts.  Mr. Hernandez has appeared before the Supreme Court en banc.
Mr. Hernadez was also a rapporteur for various international conferences in human rights, democracy, development, security and security-sector reform.  He was also a technical consultant to the Millennium Challenge Account-Philippines Threshold Program-Technical Assistance Project where he designed substantive law training programs for Ombudsman investigators and prosecutors on “life-style checks” and contract and procurement fraud, among others.  He pushed for the development and was the managing editor of the Ombudsman Desk Reference for Investigation and Prosecution.  Mr. Hernandez was also a consultant of the Integrity Project, a USAID funded program that supported initiatives to enhance the anti-corruption capabilities of the Office of the Ombudsman, Commission on Audit and the Department of Justice.  He is likewise a member of the New York State Bar.




University of the Philippines 
​College of Law 2006
Bachelor of Laws 

Mr. Tan has substantial experience in the practice of commercial and administrative law. He possesses competence in asset acquisitions, project finance, and securities. Mr. Tan is also involved deeply with the litigation of issues arising from various commercial arrangements involving leases, labor relations, and purchase agreements.
Mr. Tan was likewise exposed to legal practice in the health industry, becoming involved with the resolution of various customs issues for the Stryker corporation.  In addition, Mr. Tan participated in crafting and proposing new regulatory matters affecting the pharmaceutical industry on behalf of the Pharmaceutical and Healthcare Association of the Philippines.