A group of travelers had sued in San Francisco, claiming the deal would raise fares. They asked Judge Richard Seeborg to stop the deal from closing until a jury can hear their claims.
But the judge's ruling on Monday says the travelers have not shown that they personally would be harmed enough to stop the deal from moving forward.
The Justice Department has already said it has no antitrust objections to the deal. The airlines have said they expect it to close by Friday.