JetBlue-Spirit Deal Judge Weighs Impact on Low-Fare Passengers

No-frills travelers who rely on cheap air fares to cities like Fort Lauderdale, Florida, or Las Vegas will be the key focus of a federal judge deciding the fate of JetBlue Airways Corp.’s $3.8 billion acquisition of Spirit Airlines Inc., after a five-week US antitrust trial.

US District Judge William G. Young in Boston signaled he will need to determine whether the deal eliminating Spirit as the dominant deep-fare discounter will hurt competition on routes favored by bargain-hunting passengers and drive up prices, as the Justice Department claimed in a lawsuit seeking to block the merger.

“To me, ...