A High Court judge has suspended the signing of a contract that would hand over a Derbyshire GP surgery to a health corporation.
The local primary care trust is considering the legal challenge
An injunction issued on Tuesday has temporarily stopped the local primary care trust from letting United Health Europe run the surgery in Creswell.
Local resident Pam Smith, who is challenging the trust's decision, said people were not properly consulted.
The trust has a week to respond to Mrs Smith's demand for a judicial review.
North Eastern Derbyshire Primary Care Trust chose the firm as the preferred bidder for two surgeries, from a short list of six, in January.
The decision means the contract cannot proceed until a judge has considered the case for judicial review.
A recent government health white paper set out plans to open up primary care to the market by encouraging private companies to run GP surgeries.
Mrs Smith, who is a local parish councillor, said several other local candidates were overlooked by the trust when it considered who should run the Creswell Primary Care Centre.
Richard Smith, chief executive of United Health Europe, which is part of the US-based United Health Group, said in an earlier interview that his firm would provide a good service.
"This is a good move for local people. We will be able to bring the practices up to the standard of the best in Britain," he said.