The UK's biggest abortion provider is taking legal action to make it easier for women to complete the procedure in their own homes.
The High Court challenge, which is being contested by the Department of Health, comes after talks broke down between ministers and experts from the British Pregnancy Advisory Service (BPAS).
Ann Furedi, chief executive of the BPAS charity, said it could no longer "sit back" on the issue after a decade of "ebbing and flowing of enthusiasm" within Government.
Such enthusiasm has been "entirely dependent" on whether officials deemed it "politically expedient" for reform of abortion services to take place, she said, adding that the Department had always agreed it was safe for women to complete abortions at home.
In its action, BPAS is asking the High Court for an updated interpretation of the 1967 Abortion Act.
The Act stipulates that treatment for the termination of pregnancy must be carried out in a hospital or clinic.
This means women wanting an early medical abortion (EMA) before nine weeks' gestation must go to a clinic twice to receive the tablets in two stages.
On the first visit, women receive one mifepristone tablet to swallow and are told to return to the clinic 24 to 48 hours later.
On this second occasion, women receive a second dose of four tablets (misoprostol), which are usually inserted vaginally, can be swallowed or are dissolved under the tongue or between the cheek and the gum.
Cramping and bleeding to bring about a miscarriage usually begins one to two hours after this dose but can start sooner in some cases. The abortion is usually completed within four to six hours.
BPAS believes women should be given this second dose, with clear instructions on how to take it at home, during the one visit.