In 1856, he entered New York University, where he was awarded all prizes in freshman and sophomore year.

[3] He initially clerked in the office of John H. and Samuel Riker prior to his admittance to the bar.

[5] In 1880, Governor Alonzo B. Cornell appointed Isaacs Justice of the Marine Court of New York to fill a vacancy.

As a member of the Outdoor Recreation League, he helped established Seward Park in the Lower East Side and the Roof-Playground of the Hebrew Institute.

[8] Isaacs helped edit his father's paper The Jewish Messenger when it was founded in 1857, when he was only sixteen.

He was president of the Baron Hirsch Fund, which provided aid for Russian and Romanian Jews who immigrated to the United States.

He wrote and published several pamphlets, including "The Persecution of the Jews in Roumania" in 1875, "The Jewish Question in Russia" in 1882, and "American Israelites" in 1886.

[2] Isaacs died from heart disease in Cafe Savarin in the Equitable Building on May 24, 1904.