The District Court in Puerto Rico continued to be an Article IV court even after Puerto Rico attained its commonwealth status. However, in 1966, the U.S. Congress conferred life tenure on the federal judges of Puerto Rico, transforming the court into a full-fledged Article III district court with the same status as the other United States District Courts throughout the country.  The congressional report on the bill making this change described the change of status as being "appropriate in light of the court's caseload and the conferral of Commonwealth status on Puerto Rico," and also explained:
There is no reason why the U.S. District Judges for the District of Puerto Rico should not be placed in a position of parity as to tenure with all other Federal Judges throughout our judicial system. Moreover, federal litigants in Puerto Rico should not be denied the benefit of judges made independent by life tenure from the pressures of those who might influence his chances of reappointment, which benefits the Constitution guarantees to the litigants in all other Federal Courts. These judges in Puerto Rico have and will have the exacting same heavy responsibilities as all other Federal district judges and, therefore, they should have the same independence, security, and retirement benefits to which all other Federal district judges are entitled.
See 1966 U.S.C.C.A.N. 2786-90; see also Examining Bd. of Engineers Architects and Surveyors v. Flores de Otero, 426 U.S. at 595 n.26 (“The reason given for this [law] was that the Federal District Court in Puerto Rico ‘is in its jurisdiction, powers, and responsibilities the same as the U.S. district courts in the (several) states’.”). This important change in the federal judicialstructure of the island was implemented not as a request of the Commonwealth government, but rather at the repeated request of the Judicial Conference of the United States. See Senate Report No. 1504, 1966 U.S.C.C.A.N. 2786-90.
No similar law has been passed for the three insular territories that still have Article IV status, though there have been calls from time to time that these judges also deserve the protection of life tenure.
During this period, judges for the District of Puerto Rico were appointed by the president for 4-year terms until 1938, and thereafter for 8-year terms. The court statutorily comprised a single judge until 1961, when a second judgeship was authorized by Congress, although the position was not actually filled until 1965. Until the 1950s, when the District Court judgeship was vacant, when the judge was away from Puerto Rico, or when the court's docket became overly backlogged, sitting judges of the Supreme Court of Puerto Rico were designated to act as judges of the federal court.
Judge Ruiz-Nazario, appointed by President Harry Truman in 1952, was the first Puerto Rican to serve as a judge of Puerto Rico's federal court.
CONSEJO DE SALUD PLAYA DE PONCE v. RULLAN. 586 F.Supp.2d 22 (2008). CONSEJO DE SALUD PLAYA DE PONCE, et al., Plaintiffs v. Johnny RULLAN, Secretary of Health of the Commonwealth of Puerto Rico, Defendant. Civil Nos. 06-1260(GAG), 06-1524(GAG). United States District Court, D. Puerto Rico. October 10, 2008. As Corrected November 10, 2008. Retrieved 1 April 2013.