As a brilliant lawyer and by virtue of Royal Decree in 1893, he was appointed as magistrado suplemente (substitute judge) and holds the position until the 1896 revolution. Eustaquio married twice in his lifetime. At the age of 29, Eustaquio married Evarista Romasanta y Marquez. There were two offsprings in the name of Vicente and Felicidad who was born later in 1870. In 1848, an uncle brought Vicente to Manila to study and take up Bachelor of Arts in Colegio de San Juan de Letran and graduated with honors in 1851. He later took up theology at University of Santo Thomas. Foz’s interest in priesthood became to fade when he shifted to the college of law and earned his bachelor’s degree in 1859. After graduation, he practiced his law profession and by 1871 he was appointed as ecclesiastical attorney general or promotor fiscal of Tondo, Manila. As fiscal, he refused to be assigned to far flung provinces and instead put up a private law office and later moved to the province of Bulacan as one of province’s four accredited lawyers. Vicente Foz, together with Mena Crisologo, Francisco Tongson and Ignacio Villamor was elected as representatives of Ilocos Sur to the Malolos Congress. They became a part of the 1898 Malolos Constitution. In 1898, Eustaquio married again his

second wife – Maria Vicenta Angco

''''''who had 8 children. 

Appointed as Magistrado Suplemente in the Audiencia de lo Criminal of Vigan.