The legal status of the unimplanted embryo is the crux of the debate about reproductive technologies, the conference was told.
"I do not think it is possible to give to genetic material in a tube or on a plate the rights you and I have," said Mr John Rogers SC.
He said that Article 40.3.3, which protects the right to life of the unborn, did not extend to embryos created for in-vitro fertilisation (IVF) procedures before implantation.
"What is unborn life? Is an ovum, fertilised by IVF, a human life?" he asked.
Referring to the debate on the 1983 constitutional amendment that resulted in Article 40.3.3, he said: "It seems to me that people did not vote on the amendment as a proposition defining when life started."
He said he considered that constitutional protection was granted to embryos and foetuses being carried in the wombs of women, individuals as yet unborn, but having the capacity to be born.
"Protection is not granted to the fertilised ovum," he said. Unborn must mean capable of being born.
Dr Brendan Purcell, lecturer in anthropological philosophy in UCD, said that the Irish language version of the Constitution gave the "unborn" as "beo gan breith". This clearly did cover unimplanted embryos.
"If an embryo is not a human being, what do we understand human to be?
"There is no philosophical reason for denying to any embryo the respect due to adult human beings.
"Should the right to a child ever take away the right of a child to be born?"
He said that in certain in-vitro fertilisation procedures and experimental cloning, up to 95 per cent of the created embryos were destroyed.
The Medical Council guidelines made it professional misconduct to create embryos for experimental purposes, and, he said, he would like to see this expanded into law.
Speaking from the floor, Prof William Binchy from Trinity College said he disagreed with Mr Rogers.
"I have no doubt that the intent of the voters [voting for the anti-abortion amendment in 1983] was to protect all human beings in the pre-birth stage," he said.
Interpreting it as those with a capacity to be born was not in the words in the English version, and certainly not implied in the Irish version.
He said that if it only covered those inside the womb, it would mean that, when it became possible for babies to go through the whole gestation period outside the womb, they would have no protection.
Dr Anne McLaren, a biologist and member of the European Group for Ethics and Science, said she had sincere respect for those who believed that human life began at single-cell stage.
"But if I go into a burning building and I see a newborn baby or young child on one side, and a dish with an eight-cell embryo on the other, I know which I will choose," she said.
Prof John Bonnar, obstetrician, said it was not true that in-vitro fertilisation necessarily involved the destruction of embryos. Over 1,000 Irish children had been born using IVF, and Irish obstetricians operated to the highest ethical standards.