[3] In 1933, Fernós Isern resigned as health commissioner and went to New York City where he completed his residency in cardiology at Columbia University and thus became the first Puerto Rican cardiologist.

In 1942, he returned to head the Department of Health and the Administration of Public Housing, in addition to serving as Director of the War Effort Office for Puerto Rico.

In 1947, the Crawford Project, allowing Puerto Ricans to elect their governor, was approved by Congress and signed into law by President Harry S Truman.

[2] On June 8, 1950, the United States Senate approved Public Law 600, permitting Puerto Rico to establish its own constitutional local autonomous government.

[3] His memory is honored at the Capitol in San Juan with a bust facing the urn preserving the original Constitution of Puerto Rico.

His collected papers are held in trust at the Fernós Isern room at the Inter American University Law School in Hato Rey, San Juan.