A federal judge has expanded a lawsuit filed on behalf of two disabled children who are fighting for home care, raising the possibility of sweeping changes in the way Maine provides services to hundreds of Maine families.

U.S. District Judge Gene Carter ruled that all children with mental impairment who are not getting timely in-home services from the state will be considered plaintiffs in a case filed a year ago by two Augusta-area families.

The families say the state has failed to meet standards of care for their children that are required under federal law.

Like the class-action lawsuits that changed the way the state cares for adults with mental illness and mental retardation, this case could create court-imposed standards for the way in-home services are provided for children.

The families are not seeking any money, said Margaret Minister O’Keefe, a member of the legal team. They are asking the court to mandate reforms to the system for providing in-home care for children with mental disabilities.

“It is really the right of the children to receive these necessary services to assist them in becoming fully functioning adults, or as fully functioning as they can be,” O’Keefe said.

State officials said it was too early Friday to determine whether this case would be settled with a consent decree, like those filed by the residents of the Augusta Mental Health Institute and the Pineland Center, the state’s former facility for people with mental retardation.

The number of people who would be included in the suit also has not been determined, but court documents suggest it falls between 400 and 700 children statewide.

The ultimate cost to the state is also unknown, but the state now spends $13 million providing in-home care to about 1,400 people.

O’Keefe said the case would not likely have a large impact on Maine taxpayers, because the services the plaintiffs are demanding come though the Medicaid program. That program receives two-thirds of its funding from the federal government.