Opponents of Mayor Bloomberg’s ban on cell phones in the city schools are planning another assault, and they say this one could end in triumph.

A lawsuit brought by parents challenging the ban, which prohibits students from using cell phones in school and from bringing them to school in the first place, was dismissed by a judge this April.

New legislation expected to pass in the City Council this week could make another lawsuit impossible to shoot down, ban opponents said.

A bill that would hand parents the right to provide their children with cell phones for use “en route to and from school” is expected to come to a vote on Wednesday. “No person shall interfere with such right,” the bill says. (Organized opposition to the cell phone ban has said it agrees with the prohibition against using the devices during the school day.)

While mayoral control gives Mr. Bloomberg authority over the city schools, because the bill focuses on the trip to and from school it would not infringe on his authority, ban opponents said.

A City Council member promoting the bill, Peter Vallone Jr., a Democrat of Queens, said he hopes it will force the city to back down and let students carry phones. Barring that, he’s hoping it would encourage a judge to strike down the mayor’s ban.

The first lawsuit’s plaintiffs have filed an appeal, but their lawyer, Norman Siegel, said the case could be moot if the council forces the Department of Education to compromise.

“It’s all in the hands of the chancellor and the mayor,” Mr. Siegel said. “It’s their call, to use a pun.” A spokesman for the education department, Andrew Jacob, said the city has no plans to back down from its policy, though it is testing a plan to let students store phones in lockers just outside school buildings. Sixteen schools will have the lockers in September.

Mr. Vallone called the lockers plan wasteful, but he said expanding it to all schools would be an acceptable compromise.