Scotland's largest health board has been taken to court by Catholic staff who claim conscientious objections over abortion procedures were disregarded.
Midwifery sisters Mary Doogan, 57, and Concepta Wood, 51, say being forced to supervise staff taking part in abortions violates their human rights.
NHS Greater Glasgow and Clyde claims conscientious objections do not give them the right to refuse such duties.
The hearing, at the Court of Session in Edinburgh, continues.
Ms Doogan and Mrs Wood sought during a grievance procedure to have confirmation that they were not required to delegate, supervise or support staff in the participation and care of patients through "the processes of medical termination of pregnancy and feticide".
NHS Greater Glasgow and Clyde (GGC) rejected their application.
Both women have now gone to court seeking to have the ruling set aside in a judicial review.
They claim that the refusal to recognise their entitlement to conscientious objection was unreasonable and violated their rights under Article 9 of the European Convention on Human Rights (ECHR) guaranteeing the right to freedom of thought, conscience and religion.
They are seeking a finding that their entitlement to conscientious objection to taking part in abortions in terms of the 1967 Abortion Act includes the right to refuse to delegate, supervise and support staff involved in such work.
The women said in their petition that they are practising Roman Catholics and: "They hold a religious belief that all human life is sacred from the moment of conception and that termination of pregnancy is a grave offence against human life."
They maintain that they hold the belief that that their involvement in the process of termination is wrongful and an offence against God and the teachings of their church.
Ms Doogan and Mrs Wood, who are both midwifery sisters at the Southern General Hospital, in Glasgow, worked in the labour ward.
Ms Doogan, from Glasgow, has been absent through ill health since 2010 as a result of the dispute.
Her colleague, from Clarkston, East Renfrewshire, has been transferred to maternity assessment work.
NHS GGC, which is contesting their action, said it recognised their right not to participate in terminations under the terms of the Abortion Act.
But it maintains that it decided correctly that requiring them to delegate staff to nurse women undergoing medical terminations and to supervise and support staff undertaking that duty was lawful.
It maintains that the women's rights to conscientious objection under the legislation does not include the right to refuse such duties.
The board said that its decision respects the women's rights under Article 9 of the ECHR.