In 1946, President Harry S. Truman relieved Governor Rexford Guy Tugwell, who had served in this position from 1941, and named Piñero as governor in his place, the first native Puerto Rican appointed to that post under U.S. administration.

On May 21, 1948, a bill was introduced before the Puerto Rican Senate which would restrain the rights of the independence and Nationalist movements on the archipelago.
The Senate, controlled by the PPD and presided by Luis Muñoz Marín, approved the bill that day.
This bill, which resembled the anti-communist Smith Act passed in the United States in 1940, became known as the Ley de la Mordaza (Gag Law) when Governor Piñero signed it into law on June 10, 1948.
Under this new law it would be a crime to print, publish, sell, or exhibit any material intended to paralyze or destroy the insular government; or to organize any society, group or assembly of people with a similar destructive intent.
It made it illegal to sing a patriotic song, and reinforced the 1898 law that had made it illegal to display the Flag of Puerto Rico, with anyone found guilty of disobeying the law in any way being subject to a sentence of up to ten years imprisonment, a fine of up to US$10,000 (equivalent to $106,000 in 2019), or both.

According to Dr. Leopoldo Figueroa, the only non-PPD member of the Puerto Rico House of Representatives, the law was repressive and was in violation of the First Amendment of the US Constitution which guarantees Freedom of Speech.
He pointed out that the law as such was a violation of the civil rights of the people of Puerto Rico.

Piñero served as governor until 1949, when Puerto Rico celebrated its first popular election for the position, in which Muñoz Marín was elected governor.
During Piñero's administration, legislation was passed that later served as the basis for the economic development plan known as Operation Bootstrap.
Plans for the construction of a new international airport for the Island were also drawn up during his governorship.
From 1947 to 1951, Piñero served as U.S. representative to the Caribbean Commission.
In 1946, President Harry S. Truman relieved Governor Rexford Guy Tugwell, who had served in this position from 1941, and named Piñero as governor in his place, the first native Puerto Rican appointed to that post under U.S. administration.
On May 21, 1948, a bill was introduced before the Puerto Rican Senate which would restrain the rights of the independence and Nationalist movements on the archipelago. The Senate, controlled by the PPD and presided by Luis Muñoz Marín, approved the bill that day. This bill, which resembled the anti-communist Smith Act passed in the United States in 1940, became known as the Ley de la Mordaza (Gag Law) when Governor Piñero signed it into law on June 10, 1948. Under this new law it would be a crime to print, publish, sell, or exhibit any material intended to paralyze or destroy the insular government; or to organize any society, group or assembly of people with a similar destructive intent. It made it illegal to sing a patriotic song, and reinforced the 1898 law that had made it illegal to display the Flag of Puerto Rico, with anyone found guilty of disobeying the law in any way being subject to a sentence of up to ten years imprisonment, a fine of up to US$10,000 (equivalent to $106,000 in 2019), or both.
According to Dr. Leopoldo Figueroa, the only non-PPD member of the Puerto Rico House of Representatives, the law was repressive and was in violation of the First Amendment of the US Constitution which guarantees Freedom of Speech. He pointed out that the law as such was a violation of the civil rights of the people of Puerto Rico.
Piñero served as governor until 1949, when Puerto Rico celebrated its first popular election for the position, in which Muñoz Marín was elected governor. During Piñero's administration, legislation was passed that later served as the basis for the economic development plan known as Operation Bootstrap. Plans for the construction of a new international airport for the Island were also drawn up during his governorship. From 1947 to 1951, Piñero served as U.S. representative to the Caribbean Commission.
Jesús T. Piñero