BOSTON - JetBlue Airways Corp. is the latest airline to fall into the sights of Shannon Liss-Riordan, a Boston lawyer who has helped skycaps sue other carriers over a $2-per-bag charge at Logan Airport and other airports.

Liss-Riordan sued JetBlue last week in Boston federal court on behalf of three skycaps at Logan's JetBlue terminal: Joseph Travers of Everett, Lawrence McCarty of Revere, and Randolph Trim of Pawtucket, R.I. Liss-Riordan is seeking class action status for the suit. The three skycaps work for JetBlue contractor Flight Services & Systems.

The lawsuit alleges that JetBlue violates the state's tips law for failing to distribute portions of a $2-per-bag charge to skycaps and for not adequately notifying customers in writing that the charge is not a tip for the skycaps.

The skycaps say their earnings have dropped significantly since JetBlue began charging the fee, starting for a period of time in 2006, and then beginning again in February. They say that fewer passengers tip the skycaps now, partly because they don't know that the $2-per-bag charge is not a tip.

Liss-Riordan said airlines such as JetBlue are intentionally profiting from the fact that the charge looks like a tip, and are taking advantage of the skycaps to generate revenue from the baggage fees.

"They are playing off this misunderstanding that they know people will have in order to get people to be willing to pay off this money," she said. "They know passengers are willing to hand out cash at the curbs to skycaps who are willing to help them."