He was a member of the House of Nobles in 1890, supporter of Liliuokalani and ironically a captain in the pro-annexation Honolulu Rifles.

He was appointed by President of the United States Woodrow Wilson to the office after the term of Lucius E. Pinkham.

The omnibus bill also contained language that made it difficult for “Orientals” from winning homesteads, and barred them from federal jobs in favor of Hawaiians.

McCarthy also proposed that the military replace self-government in order to negate possible bloc voting by the large Japanese population in Hawaii.

In return, he was given a job as Washington representative of the Honolulu Chamber of Commerce, and later general manager of Hawaiian Dredging Co. during which he worked on the Waikiki Reclamation project which resulted in the construction of the Ala Wai Canal.