A group of families have gone to the high court in London to try to overturn local authority cuts to special educational needs (SEN) spending, claiming their children are already failing to get the support they require.

The judicial review against the London borough of Hackney is the latest in a series of legal actions launched by parents across England as struggling local authorities turn their eye to ballooning special needs spending in order to make savings.

The parents, from Hackney, are challenging the legality of the council’s policy of splitting SEN funding into five bands, rather than tailoring spending to meet the needs of each individual child.

They are also challenging the council’s decision to reduce the amount in each band by 5%, which they say was done without proper consultation. They argue that the council’s new education, health care (EHC) plans – legal documents that detail a child’s additional needs – are unlawful.

Among the families taking action are John and Hilary Roden, carers for their granddaughter, Hope, aged five, who has a rare genetic condition called glutaric acidemia which means her body cannot break down certain foods.

“Hope is already not receiving the support and care she needs at present so we feel this is only going to get worse if these cuts go ahead,” said Hope’s grandfather. “We feel that throughout all of this the council has just ignored our concerns.”

Dana Thompson, whose daughter Sade, 16, has been diagnosed with narcolepsy and cataplexy, said: “We feel that we have had to fight the council every step of the way for Sade to be granted what she needs. If these cuts go through we fear that we will be back to square one.”

Hackney council denies its policies will result in a failure to provide adequately for children with SEN. It says it is committed to meeting all SEN provision in children’s EHC plans and contests the banding system leads to underfunding. It further claims the 5% cut can be absorbed by schools without compromising provision.

As the two-day hearing started on Wednesday, another crowdfunding campaign was launched to raise sufficient funds to legally challenge proposed cuts to SEN spending in Portsmouth.

In this latest case, a single mother of two children with SEN and disabilities says she is seeking to raise £6,000 to bring a judicial review against planned cuts of almost half a million pounds.

The woman, who describes herself as homeless and disabled, said her youngest child has suspected autism spectrum disorder and has SEN support to attend a mainstream primary school, while her older child has an EHC plan and attends a specialist school. “I believe these cuts may be unlawful and if introduced could have a devastating impact on all children with special educational needs/disabilities in Portsmouth,” she said.

Anne-Marie Irwin, who specialises in public law and human rights and is acting for the Hackney families, called on the council to rethink its policies. “The families are hugely concerned by the steps taken by this council and feel they do not ensure that each child will receive the support they need. We appreciate that local authorities face significant budget challenges but they still have a duty to ensure all decisions comply with the law.”