Anti-abortion campaigners have told judges a "buffer zone" outside a London clinic defies their right to protest.
Attendees of a vigil run by the Good Counsel Network (GCN) have challenged a ban on protests targeting users of the Marie Stopes facility in Ealing.
The 330ft (100m) buffer zone was imposed by Ealing Council in April 2018 after women complained of intimidation.
Council lawyers said some women had been "significantly affected by their encounters with the activists".
This is now being challenged at the Court of Appeal by Alina Dulgheriu and Andrea Orthova, who regularly attend vigils held by the GCN.
GCN's lawyers argued the order "criminalises acts of prayer".
The said the ban interfered with the protesters rights under the European Convention on Human Rights to freedom of expression.
Lawyers representing Ealing Council said the buffer zone should remain, and that encounters with the activists still affected some women who had abortions many years ago.
The appeal is due to last two days.