The UK's biggest abortion provider has asked the High Court to interpret the law in line with modern science and make it easier for women to complete terminations at home.
The British Pregnancy Advisory Service (BPAS) urged a judge to rule that the 1967 Abortion Act allows women to take the second dose of tablets for an early medical abortion (EMA) without having to visit medical premises.
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.
Nathalie Lieven QC, appearing for BPAS, argued that "medical science has moved on a great deal" and it is safe for women actually to self-administer the second dose at home.
Ms Lieven asked Mr Justice Supperstone, sitting at London's High Court, to rule against Health Secretary Andrew Lansley, who says that the law requires all tablets to be administered on clinical premises.
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.
Pro-life campaigners say BPAS's intention is to make abortion "little more than a pill-popping exercise".
The Society for the Protection of Unborn Children (SPUC) has been given permission to intervene in the case and put its views to the judge.