The Seanad has heard calls for President Michael D Higgins to pardon a 79-year-old woman who is serving a three-month prison term.
Margaretta D'Arcy, who suffers from Parkinson's Disease, was jailed last week for illegally accessing a runway at Shannon Airport.
President Higgins' wife Sabina visited Ms D'Arcy in prison over the weekend.
But Sinn Féin senator Trevor Ó Clochartaigh says the Constitution gives the President himself the power to pardon her.
Earlier, President Higgins defended his wife's visit as "a private and personal visit".
Mrs Higgins went to Limerick prison on Sunday to meet 79-year-old Margaretta D’Arcy, who was jailed last week after refusing to sign a bond pledging not to protest again at Shannon Airport.
The writer, playwright and member of Aosdana had been charged after protesting on the runway over its use by the US military.
Mr Higgins told TodayFM: “Sabina was visiting a friend of long-standing whose health is frail and who was a fellow artist with Sabina and who were in many performances together.
“Sabina is a person who can speak for herself as well and is person of very good judgment. We do a lot of things together but we do a lot of other things as well. It’s not for me to comment. It’s a private and personal visit but it really is a private and personal visit to her friend who is fragile and who is a fellow artist.”
Tánaiste Eamon Gilmore also said the visit was appropriate.
Both Mr and Mrs Higgins have known D’Arcy for years, both through living in Galway and through connections in the arts.
The visit came to light after her son Finn Arden and two other anti-war activists, retired army officer Edward Horgan of the Shannonwatch group and Niall Farrell of the Galway Alliance Against War, visited her in prison yesterday.
D’Arcy is undergoing treatment for cancer. Last month she was given a three-month suspended sentence for an illegal incursion on the runway at Shannon Airport in October 2012. She was jailed last week after refusing to sign the bond.
The Galway Alliance Against War said D’Arcy has made clear that she is willing to sign a form committing to keep the peace but only if there is no direct reference to Shannon.