A Honolulu woman is suing the state on behalf of other part-time public school teachers who say the Department of Education has underpaid them over the past 10 years and owes them millions of dollars in back pay.

The class-action lawsuit was filed yesterday in Circuit Court by Dianne Kawashima, a part-time teacher since 2001. Kawashima says the DOE has "cheated" her and thousands of other part-time temporary DOE employees from July 1996 to July 1, 2005.

The lawsuit seeks an unspecified amount in damages.

Greg Knudsen, DOE spokesman, said his department had not seen the lawsuit and could not comment.

Paul Alston, attorney for Kawashima, said the lawsuit is similar to one filed in 2002 by 9,000 substitute teachers who accused the state of failing to follow a pay scale that linked daily wages for substitutes with salaries of regular teachers. Last December, Circuit Judge Karen Ahn ruled in favor of the substitutes, but she said they could receive back pay only from November 2000 because of the statute of limitations.

Still, the amount owed to the substitutes is estimated at $15 million. The state has yet to decide if it will appeal Ahn's ruling.

Alston said the pay for part-time teachers is tied to the substitute teacher scale, and since the court has ruled the substitutes were underpaid, the part-timers were also. He said the hourly rate for part-time teachers is one-seventh of the daily rate for a substitute.

In their lawsuit, the substitutes said they were owed $150 a day, rather than the $112 they were getting until July 1, 2005, when the Legislature increased their three-tiered pay scale to $120 to $140. There is at least one bill in the Legislature now that would address that issue.

"Part-time teachers are to be paid hourly rates which are directly linked to the pay for the substitutes. Because they cheated the substitutes, they cheated part-time teachers," Alston said.

The lawsuit said that on any given day, "hundreds of part-time employees" work under contract with the DOE.

Knudsen said part-time teachers are limited to 17 1/2 hours a week and most are hired at the school level. He said it is "hard to pin down the number" of part-time teachers under contract with the DOE.

Unlike substitutes, part-time teachers usually are hired for a specific assignment, such as for summer school, driver's education, sports coaching and band instruction, Alston said. These teachers typically don't spend a full day teaching, he said.

"Because of the numbers of people out there, I think it's a smaller group than the substitute teachers, but it'll be some millions of dollars (in damages)," Alston said.

Reach Curtis Lum at culum@honoluluadvertiser.com.