The American Civil Liberties Union of Hawaii is suing the state, arguing a child care assistance program that provides preschool tuition subsidies for low-income families violates the state and U.S. constitutions by providing public funds for religious observations and teachings.

The lawsuit, filed Monday in Circuit Court, names Patricia McManaman in her official capacity as director of the state Department of Human Services, which runs the Preschool Open Doors program.

The suit alleges the subsidy program is unconstitutional because "the state places no limits on how a religious institution may spend the public funds it receives (and) as such, the state directly funnels public funds to religious institutions that embrace nonsecular teaching and instruction for preschool children."

In addition to the constitutionally mandated separation of church and state, the Hawaii Constitution prohibits public funds from being spent to support or benefit private educational institutions.

"Families that wish to use their private funds to send their children to religious institutions for preschool have a right to do so," the complaint says. "While private preschool providers are entitled to base their curricula on religious teachings, and are likewise entitled to incorporate religious observances into their educational programs, a constitutional problem arises when public funds are funneled directly to these religious institutions for the purpose of instructing children regarding religious observances."

The lawsuit is asking the court for an injunction prohibiting the state from paying religious providers to expend public funds on religious instruction.

A spokeswoman for the Department of Human Services said Tuesday the department was reviewing the complaint and had no comment. The state attorney general’s office did not immediately respond to a request for comment.

A spokeswoman for the ACLU of Hawaii said officials were unavailable for comment Tuesday, but added that the nonpartisan nonprofit would be issuing a statement Wednesday.

While the lawsuit argues the state directly provides funding to religious institutions, the Preschool Open Doors website says monthly preschool tuition subsidies are provided directly to qualified families for up to one year.

An eligible family can receive up to $710 a month for its child to attend a licensed preschool. If awarded subsidies, families can select any of the approximately 1,000 child care programs licensed by the state, including about 650 preschools.

"The subsidy goes to the parent, and they make the choice as to where they place their child. It really is a child-care subsidy program," said state Sen. Jill Tokuda, chairwoman of the Senate Education Committee.

Tokuda said the lawsuit caught her off guard, adding that ACLU officials haven’t raised these concerns to lawmakers.

"I think it would have been preferable if the ACLU had concerns that it could have been addressed outside of a lawsuit," she said.

The Preschool Open Doors program in recent years has provided tuition assistance for about 325 preschoolers with annual funding typically in the $1.5 million range.

Last year lawmakers scaled down Gov. Neil Abercrombie’s early education initiatives and converted a $25 million school-readiness proposal into a $6 million expansion of Preschool Open Doors. (The draft state budget advanced by the Senate this week includes an additional $3 million for Preschool Open Doors.)

The funds are intended to help ease the transition to a higher age requirement to start kindergarten and the elimination of junior kindergarten at public schools next school year, which is expected to affect an estimated 5,100 children.

A proposed constitutional amendment that will go before voters in November could eliminate the ban on public funds benefiting private educational institutions.

If passed, it would allow the state to contract with private preschool providers to build added capacity to eventually serve all of the state’s 17,200 4-year-olds.

The proposed amendment is critical to Abercrombie’s push for universal preschool. He has said that a combination of public preschools, private preschools and state-funded slots in private schools is likely needed.

Hawaii is one of 11 states without state-funded preschool. About 40 percent of keiki attend preschool, at an average $803 a month.

CORRECTION: The photo with this story was taken on April 3, 2013. An earlier version of this story said the photo was  taken Wednesday.