Halpern was the referee for several notable bouts in 1999: the Lennox Lewis–Evander Holyfield rematch at the Thomas & Mack Center in which Lennox was the winner by unanimous decision; the Oscar De La Hoya–Félix Trinidad welterweight championship fight at Mandalay Bay in which Trinidad won by majority decision (billed as the Fight of the Millennium, the fight set a pay-per-view record for a non-heavyweight fight); also in 1999, Halpern officiated the De La Hoya–Ike Quartey fight in which De La Hoya won by split decision.