The UK's biggest abortion provider is seeking a High Court ruling to make it easier for women to complete the procedure at home.
The British Pregnancy Advisory Service (BPAS) wants an updated interpretation of the 1967 Abortion Act to allow women to take the second dose of tablets for an early medical abortion (EMA) at home.
At present, the first and second dose must be taken in a clinic or hospital under supervision. Most women go straight home after the second dose.
BPAS says the UK should follow other countries, including the US, France and Sweden, in allowing women to safely complete their terminations without repeated visits to a clinic.
The Department of Health will contest the legal action, scheduled for January 28, while pro-life campaigners said BPAS' intention was to make abortion "little more than a pill-popping exercise".
Ann Furedi, chief executive of BPAS, said it could no longer "sit back" on the issue after a decade of "ebbing and flowing of enthusiasm" within Government. She said the legal action would not alter who could get an abortion but would simply mean that those who were entitled to one could complete the procedure in their own homes.
BPAS argued that women suffer unnecessary anxiety about having an abortion on their way home from the clinic, especially those who have travelled long distances or who use public transport.
Dr Patricia Lohr, medical director of BPAS, said a second visit to the clinic is "medically unnecessary". She added: "Most women prefer to go home because it's a private setting, it's comfortable, they can have their friends with them, they can have their family with them, they can have their partner."
The pro-life group, the Society for the Protection of Unborn Children (SPUC), said it would seek to intervene in the case and a statement from the charity Life said: "Clearly, BPAS' intention is to increase access to abortion yet further, by making it little more than a pill-popping exercise. This has shifted the debate away from whether or not a woman has an abortion at all, simply to how and where she does it."
A spokeswoman for the Department of Health said it was a matter for the courts to decide. "However, it is the Government's view that the words 'any treatment for the termination of pregnancy' under Section 1(3) of the Abortion Act 1967 cover both the prescription and the administration of the drugs used in abortion," she said. "In the Government's view, this means that both tablets used for medical abortion must be administered on premises which have been approved under the Abortion Act. For this reason, the Government is contesting this case."