Peroni Sosa Tellechea Burt & Narvaja (PSTBN) is one of the largest firms in Paraguay. PSTBN was established in 1968, growing with a high international profile, strong client base and diversified areas of specialization. Through its members, PSTBN has been an active participant in legal innovation in Paraguay, advising the Government on development strategies, working closely with the Congress to enact new legislation, and taking active part in University education.

PSTBN offers a broad range of legal services for clients involved in international and local transactions in Paraguay. Firm specialization includes mergers and acquisitions, foreign investment, maritime and aviation, telecommunications, banking and international finance, mineral and oil exploration projects, labor relations, general civil litigation, taxation, counseling before local government agencies and legislative bodies, maquila projects, franchising and licensing agreements, and intellectual property matters.

Representation in the courts and administrative agencies is an important activity of PSTBN, as plaintiffs or defendants in several landmark civil and commercial cases. The Intellectual Property department, supported by the latest technology, covers every aspect of trademark, copyright and patent practice, and commercial use within Paraguay by foreign and local companies. PSTBN specializes in foreign investments and taxation, and has published important reference books titled Paraguay, Laws and Economy, Commercial and Investment Law (Paraguay), Temas de Derecho Tributario (Tax Law Matters), Regimen de Maquila (Maquila Regime)and Ley 125/91 Comentado y Concordado (Tax Law 125/91).