The Court of Appeal last week granted an appeal to the Lords to decide whether the Human Rights Act covers non-public sector organisations providing council services. Non-public sector bodies running care homes are exempt from the Act.
Help the Aged welcomed the decision as "a step towards providing protection for thousands".
Sonya Sceats, policy officer at the British Institute of Human Rights, said: "Parliament did not want the outsourcing trend to lead to users of public services being robbed of their rights."
But the National Care Association warned against "interfering with service providers' ability to make decisions".