Casiano S. Carin was born on August 13, 1897 in Cawayan, Dalaguete, Cebu. He was admitted to the Bar on December 31, 1925 earning him the title of "The First Lawyer of Dalaguete."
Casiano was the son of Santiago Perez Carin and Emeliana Selerio. The brothers and sisters of Casiano were Procia (married Moises Villahermosa), Felisa (married Eleuterio Debalocos), Eluminada (married Filomeno Dicdican Villahermosa), Alejandro (married Francisca Belcina), Potenciano (married Anita Osorio), Fausta, Remegia (married Juan Cisneros), and Felicidad.
Casiano married Avelina Osorio and they had the following children: Oscar, Santiago, Lino, Baby and Jesus.
He was a successful lawyer, with big companies as clients, one of which was the Don Mariano Jesus Cuenco's 'Bisaya Land Transportation Company." Casiano was also the lawyer of Filipino Bus Company. He even handled the case of the bus company that reached the Supreme Court that was decided on February 16, 1933. Casiano's co lawyer was the famous and brilliant Manuel C. Briones.
It was also Casiano who represented Roberto Diama and Cirilo Paglinawan involing a land dispute of a property situated in Ronda, Cebu. The case reached the Supreme Court and was decided En Banc (entire court deciding) on December 31, 1942.
Casiano was proclaimed as candidate of the Partido Democrata, during the Cebu Provincial Convention held on May 6, 1928. Casiano was the party's candidate of the then 4th Congressional District (Dalaguete at that time was part of the district, together with Argao). The convention was held at Cine Ideal and was presided by Nicolas Rafols. Vicente Y. Sotto was the party's candidate for Senator.
In the 1931 election, Casiano who was the Partido Democrata's candidate for the 4th Congressional District was replaced by Agustin Kintanar.
While Casiano lost in the previous elections, his glory days were yet to come. In the 1934 election for the Constitutional Convention held on July 10, 1934, Casiano won and became part of the 14 delegates allocated for Cebu. There were 45 candidates in Cebu who vied for the position as delegate for the first constitutional convention after the Americans occupied the Philippines. It was the country's first constitutional convention that delegates were elected by the Filipino people.
The fellow delegates of Atty. Casiano S. Carin, who were the best and the brightest then and considered unmatched even up to the present, were Manuel C. Briones (the street fronting Cebu City Hall is named after him), Filemon Sotto (a street is also named after him), Vicente Y. Sotto, Mariano Jesus Cuenco, Nicolas Rafols, Paulino Gullas (Founder of THE FREEMAN), Antonio Mansueto, Antonio Ybanez, Cesar Kintanar, Dionisio Niere, Felismeno Rivera, Juanito Maramara, and Hilario Moncado
Aside from Casiano, other members of the Carin Clan that became lawyers were Potenciano, a brother, became a lawyer on December 23, 1937, Avelina O. Carin, a graduate of the University of Mindanao (then called Mindanao College) became a lawyer on April 1, 1953, Napoleon O. Carin (January 21, 1955), Samuel B. Carin (January 8, 1954), Romeo B. Carin (March 9, 1957), and Eric Carin (April 28, 1995).