The Catholic Church has left the threat of excommunication hanging over the heads of Catholic members of the Dail who vote for the abortion legislation in its current format.

Cardinal Sean Brady yesterday refused to be drawn on the consequences for either Catholic ministers who introduce the legislation or those TDs who vote for it as it stands.

He was speaking to the media at Knock shrine in Co Mayo, where a national prayer vigil for the right to life of mothers and babies was held.

Asked if a TD who voted for the legislation as published would not automatically be excommunicated and should not therefore present himself/herself for Holy Communion, Archbishop Brady replied: "That is down the line at the moment, as far as we are concerned.

"It (our job) is to convince the electorate first of all and the legislators."

Pressed on the matter, Cardinal Brady pointed out that the exact legislation that would be introduced was not yet known.

"We know what the law is about excommunication, about abortion, that's a fact.

"But, as I say, the most important issue at this moment is to win the hearts and minds of the people of Ireland to decide with the pro-life," the cardinal said.

He described the proposed legislation as morally unacceptable and suggested that it may amount to evil.

Cardinal Brady was responding to a question asking if it was also morally unacceptable for a Catholic legislator to introduce it.

"We're trying to persuade them not to introduce it. In addition to doing good, we also have to oppose evil and to oppose a law that would take away fundamental rights from people. It should be opposed."

The message from yesterday's event in Knock, which was attended by the former Taoiseach John Bruton, was that human life was very precious and that any attempt to destroy human life was unacceptable morally.

Cardinal Brady said: "We are planning to mobilise, in the sense of making people aware of the issues, the very important issues that are at stake in this debate and in that way they would influence those who they can influence, namely the legislators.

"But it's a shared purpose. The legislators legislate for the common good.

"We do not think that abortion can form part of the common good at any stage and therefore we are trying to campaign to bring about that change of mind."

He agreed that the job of legislators was to legislate, adding: "But I don't think they have power over life, none of us have absolute power over life.

"They say they have got it from the people, but the people cannot give something that they haven't got themselves, namely the power over life.

"We have certain power over our lives, but not when we come into life or when we end life," Cardinal Brady added.

Yesterday's event was attended by an estimated 4,000 people.

The organisers had been hoping for an attendance of up to 10,000.

Irish Independent