The National Association of GPs has started a legal challenge to the Health Service Executive's plan for free GP care for the under-sixes.
The action was taken by Co Clare based GP, Dr Yvonne Williams, who wants the introduction of the new scheme postponed until the NAGP has an opportunity to negotiate the scheme on behalf of its members.
It is claimed the proposed scheme will result in changes to Dr William's General Medical Services contract with the HSE.
She claims the changes to her contract are being imposed on her unilaterally.
She also says the exclusion of the NAGP from the negotiation of the new contract has "gravely prejudiced" her.
Her action is being supported by the NAGP, which claims the HSE has acted in breach of contract.
Mr Justice Anthony Hunt granted Dr Williams permission to serve short notice of the proceedings against the HSE.
The application was made ex-parte, where only one side was represented in court.
The judge made the matter returnable to Wednesday of next week.
In a sworn statement grounding her application, Dr Williams said she also fears if she were to refuse to sign she would put the future of her practice in jeopardy.
If she did not sign, the parents of her under-six patients that have medical cards would move to whatever practice the HSE assigned their children to.
In addition private patients under the age of six years would also leave her practice to avail of free treatment elsewhere.
Dr Williams said she was being placed in an impossible position of either signing a new contract, which she believes will compromise her patients' care, or face having to close her practice.
Through her solicitors she asked the HSE to postpone the introduction of the new scheme, but they have failed to do so.
As a result she has launched the High Court proceedings seeking injunctions, including one restraining the HSE from removing any patients under the age of six from her GMS list until the proceedings are determined.
In a sworn statement to the court supporting Dr William's action, NAGP chairman Andrew Jordan said the organisation, which has 1281 members, has been "willfully excluded" from talks concerning the under-six scheme and changes to the GMS scheme.
The new contract gives the HSE the power to remove under-sixes' patients from GPs with an existing general medical service contract, if they refuse to sign the new deal, and to transfer these patients to a GP who supports the new scheme.
The HSE has already said it wants all GPs to have signed up by next Monday 25 May and parents to sign up in June.
This would then allow the service to start on 1 July.
At the end of April, the HSE issued GPs with the proposed new contract.
It followed agreement reached after lengthy talks between the Irish Medical Organisation, the HSE, and the Department of Health.
This week the IMO said GPs are very divided on the issue and are finding it difficult to make a decision.
The Irish College of GPs, which represents 2,700 family doctors, recently called for an extension to the 25 May deadline for signing up, to allow comprehensive consideration of all aspects of the contract.
A recent survey by the NAGP of all GPs found that just 2% had signed up so far.
Under the plan, along with free GP care, children under-six will have wellness checks at ages two and five and those with asthma will have a programme of care for the condition.
Meanwhile, the Competition and Consumer Protection Commission has written to the NAGP expressing its grave concerns that the recent conduct of the association amounts to an ongoing and escalating campaign designed to encourage its members to engage in a collective boycott of the under-sixes contract, contrary to EU and Irish competition law.
Commission chair Isolde Goggin said it has today written to the NAGP to advise them that their actions risk contravening competition law.
The commission said it will continue to closely monitor developments and will, if necessary, take action to stop specific anti-competitive conduct of the NAGP and its members.