Wilfredo Rodriguez Diaz (plaintiff), a 17-year-old, was seriously injured when a vehicle driven by Marcel Sierra Martinez struck his motorcycle (defendant). The accident occurred in Puerto Rico, where both men resided. Rodriguez Diaz was taken to a nearby hospital (defendant) for emergency treatment. While there, Rodriguez Diaz claimed that hospital personnel caused him to suffer a bone infection and an aggravated leg injury. Rodriguez Diaz was subsequently transferred to a different hospital (defendant) where he claimed to suffer additional maltreatment. Rodriguez Diaz moved from Puerto Rico to New York and turned 18. Rodriguez Diaz filed suit individually and on behalf of his parents as next friends in federal district court in Puerto Rico against Sierra Martinez and the two hospitals. For jurisdiction, Rodriguez Diaz alleged diversity of citizenship under 28 U.S.C. § 1332. In his complaint for negligence and medical malpractice, Rodriguez Diaz alleged that although his parents were residents of Puerto Rico, he was a resident and a domiciliary of New York. In New York, the age of majority was 18. Under Puerto Rico law, the age of majority was 21. The United States District Court for the District of Puerto Rico dismissed Rodriguez Diaz’s complaint for lack of diversity jurisdiction. The court held that because Rodriguez Diaz had not attained the age of majority under Puerto Rico, Rodriguez Diaz was a minor. As a minor, Rodriguez Diaz’s domicile was that of his parents. Because all the parties were domiciled in Puerto Rico, the court concluded that it lacked jurisdiction to entertain the suit. Rodriguez Diaz appealed.