The 55-year-old Hadley was recruited to New York City Opera in the late 1970s, reportedly by Beverly Sills, and went on during the 1980s and '90s to perform and record lyric and bel canto tenor roles with major opera houses in Europe and the U.S., including the Metropolitan Opera, Lyric Opera of Chicago, San Francisco Opera, Vienna State Opera, Royal Opera (Covent Garden), La Scala, and the Glyndebourne, Aix-en-Provence and Salzburg Festivals. In 1999, he created the title role in John Harbison's opera The Great Gatsby at the Met; he repeated the role when the Met revived the opera in 2002. That was his last appearance at the house.

Hadley frequently performed the Broadway and operetta repertoire as well; indeed, two of his most celebrated recordings are the 1988 EMI release of the complete Show Boat (which also featured Teresa Stratas and Frederica von Stade) and Leonard Bernstein's late recording of his own Candide (alongside June Anderson, Adolph Green and Christa Ludwig).

In recent years Hadley's operatic career had fallen off, amid talk among the opera community that he was having vocal difficulties. He did perform symphonic pops concerts, however, and appeared with smaller companies. His most recent operatic engagement was as Pinkerton in Madama Butterfly with Opera Queensland in Brisbane, Australia.

During the past year Hadley was more in the news for legal troubles than musical efforts: this past February he was exonerated of all charges stemming from a May 2006 arrest, made while he was sitting in the driver's seat of a parked car, for driving while intoxicated.

While that story ultimately ended well, some sources have indicated that Hadley had been dealing with other problems recently. "I know he's been in really bad trouble," Harbison told the Times. "He's been very depressed."