A lawsuit accusing Phoenix, Ariz.-based Swift Transportation Corp. of routinely shorting its drivers in pay will move forward as a class action after a long and circuitous route through the Arizona court system.

The case claims that rather than paying drivers on actual miles driven, the company calculates mileage using a software program. The suit claims that in doing so, the program, on average, underpays drivers by 7 percent to 10 percent.

According to court documents, Swift Transportation's manager of contract finance from 1998 until 2002 admitted the software consistently underreported the mileage that drivers actually log by an average of 6 percent.

The lawsuit alleges breach of contract for not paying the correct amount and breach of the implied covenant of good faith and fair dealing based on Swift Transportation's adoption of a system that underpays drivers.

The lawsuit was first filed against Swift Transportation in early 2004, but the motion to certify it as a class action was initially denied by a Maricopa County (Arizona) Superior Court judge. The judge's decision was appealed by plaintiffs' attorneys at Hagens Berman Sobol Shapiro LLP, and the Arizona Court of Appeals reversed the lower court's decision.

The appellate court's decision to certify the suit against Swift Transportation as a class action, however, was then overturned by the Arizona Supreme Court on procedural grounds. The Arizona Supreme Court held that the appellate court lacked the jurisdiction to review the decision by the trial court not to certify the suit as a class action.

The case was sent back to the Maricopa County Superior Court, where attorneys for lead plaintiff Leonel Garza and the class filed a renewed motion to have it certified as a class action. The court granted that motion Thursday.

"It's been a long and difficult road to get to this moment, but we're happy that the court ruled in our favor," said Hagens Berman attorney Rob Carey. "We've heard from numerous Swift drivers that the company's mileage calculation method cheats them out of honest and hard-earned compensation. These drivers deserve their day in court, and now they'll get it."

Maricopa County Superior Court Judge J. Richard Gama ruled Thursday that the class for the case against Swift Transportation encompasses "all persons in the United States, including those who were employed by Swift as employee drivers on or after Jan. 30, 1998 or contracted with Swift as owner-operator drivers on or after Jan. 30, 1998, who were compensated by Swift by reference to miles driven."