In 1908, Buckley moved to Mexico where, together with his brother Claude, he founded the law firm of Buckley & Buckley to represent major American and European oil companies operating in Mexico. In 1912, he opened an office with his other brother Edmund in Tampico. In 1913 Buckley founded and became President of the Pantepec Oil Company based in Tampico. In 1914 during tensions with the United States (US), President Huerta appointed Buckley counsel for a convention organized by Argentina, Brazil, and Colombia. The nations, known as the ABC Powers, were working to mediate relations between Mexico and the US because of their implications for Latin America. Buckley turned his legal practice over to his brothers to speculate in real estate and leasing of oil lands.