The High Court will give judgment today in the row over An Post's decision to have mail stamped with a Fianna Fáil slogan.
Labour Party Senator Joe Costello, a Dáil candidate in the general election, is seeking an interlocutory injunction restraining An Post from attaching any political slogan to postal packets sent by members of the public through the mail.
Mr Costello objects to the stamping of mail with the slogan: "Fianna Fáil, The Republican Party - A Lot Done - More to Do". The slogan is being stamped on mail under the terms of a contract which extends from March 1st last to May 31st.
In an affidavit, Fianna Fáil general secretary Mr Martin Macken rejected the assertion that his party's contract with An Post amounted to monopoly abuse by An Post.
Mr Macken said the postal service had sent out a brochure offering postmark advertising to all political parties, including the Labour Party.
Mr Paul Sreenan SC, for Fianna Fáil, said when a person posted a letter, they effectively lost possession of it.
Because An Post had for years been attaching advertisements to mail, the sender of a letter must know there was a reasonable chance an advertising mark might appear on their letter.
No one had a right to dictate to An Post the terms under which post may be delivered.
Fianna Fáil, like other organisations, had a basic and constitutional right to communicate its message.
Earlier, Mr Brian O'Moore SC, for Mr Costello, said An Post had no right to trespass, tamper or interfere with property owned by either the sender or addressee but held by it.
Neither An Post nor Fianna Fáil indicated it had any such right.
The contents of an envelope were never the property of An Post. The envelope containing those contents belonged either to the sender or addressee but never to An Post. Mr Brian McGovern SC, for An Post, said it would be a perversion of the English language to describe the franking of an envelope as tampering.
His client's placing of an advertisement on a letter was done with lawful authority and as part of a service which was available to all political parties.
People who committed items to the post knew ought to know there was likely to be an advertisement or franking on their mail.
Mr Justice O'Sullivan said that he would give his decision on the case today.