Judge rules American, JetBlue must undo Northeast partnership

BOSTON — American Airlines and JetBlue Airways must abandon their partnership in the northeast United States, a federal judge in Boston ruled Friday, saying that the government proved that the deal reduces competition in the airline industry.

The ruling is a blow for the airlines, which have said that their deal helps consumers by creating a stronger competitor in the Northeast to Delta Air Lines and United Airlines.

But U.S. District Judge Leo Sorokin wrote that through their alliance, American and…