Deutsche Post AG's expansion in the U.S. ground and air parcel delivery market may be slowed by its rivals United Parcel Service Inc and FedEx Corp which are seeking a regulatory review. A U.S. judge was scheduled to begin a hearing on Tuesday to determine whether Astar Air Cargo Inc, a Miami-based airline that flies for Deutsche Post's DHL unit, violates a law barring foreign control of a carrier. The judge's decision, not thought to be announced before December, may result in Deutsche Post having to change the way it does business in the United States. A win by Deutsche Post’s rivals would slow or raise costs for Deutsche Post's advance in the US, the biggest delivery market, worth an estimated $50.2 billion a year, Brian Clancy of freight-consulting firm MergeGlobal Inc. told Bloomberg.