It was some 21st birthday present.  When Pablo Carranza turned 21 in September, California’s Medicaid agency notified him that the around-the-clock nursing care he receives at the Chula Vista, Calif., home he shares with his mother would be sharply cut back.

Carranza has muscular dystrophy and can only move his left thumb and his eyes. The nurses, paid for by Medi-Cal, the joint federal-state program for low income people and those with disabilities in California, have long monitored Carranza’s ventilator and feeding tube. They also cleared fluids from his lungs and lifted him into his wheelchair. But like many other states, California’s Medicaid benefits are much more generous for disabled children than for adults.

“We call it the nursing cliff,” said Elissa Gershon, an attorney with Disability Rights California. “When they turn 21, their needs haven’t changed, but the services available are much more limited.”

In a lawsuit filed in federal court in Sacramento, Calif., Tuesday, Carranza asked a judge to stop the state’s Medicaid agency from reducing his in-home nursing care, arguing that the limited hours would force him into an institutional facility, thereby violating his civil rights under the Americans with Disabilities Act.

A spokesperson for the California Department of Health Care Services, which administers the state’s Medicaid program, said the department could not comment on pending litigation.

States that have negotiated waivers from federal Medicaid rules have tremendous discretion over how much home-based nursing care they will pay for, and that has made these so-called optional Medicaid benefits an easy target for lawmakers in California and other states who have faced punishing and persistent budget deficits.

But the reductions in health care spending since the start of California’s fiscal crisis in 2008 – more than $15 billion – are coming into conflict, legal advocates say, with federal protections for disabled people. The Americans with Disabilities Act, signed by President George H.W. Bush in 1990, along with subsequent court rulings, require that states help people with disabilities to remain in their homes or in their communities – and out of institutions like nursing homes or psychiatric hospitals – for as long as possible.

“By placing people at risk of institutionalization,” said Gershon, “they are violating the mandate of the ADA.”

There is no disagreement that placing Carranza in an institution would cost the state more: Home-based nursing costs the state $180,000 a year, the lawsuit alleges, while the cost of one year at a facility is estimated to cost $270,000. But because of arcane rules that govern the state’s budgeting process, the budget line items for home-based care, which are included in California’s waiver, and those for institutional care are considered separately.

Disability rights groups have found some measure of success in turning to federal and state courts for relief from state budget reductions. They have managed to thwart – or at least blunt – cuts to adult day health centers which offer health care services, physical therapy, shared meals and other activities to seniors and disabled people, and they have turned to the courts to stop reductions in Medicaid reimbursement rates. There have been individual cases in Illinois and Texas, similar to Carranza’s suit, in which young adults turned 21 and had their home nursing significantly reduced but were later found to be entitled to a reinstatement of state-provided assistance.

For now, Pablo Carranza’s mother, Leticia Martinez, said the nurses continue to come each day to her home. The nurses’ employer, she said, are covering the costs until a final decision is made.