The Garda has no power to stop known troublemakers from entering the State in the run-up to the anticipated May Day protests because there is no preventive detention legislation on Irish statute books. Gardaí will only be able to make arrests if trouble breaks out.
In recent months the Garda has been working closely with Interpol, Europol and other international police organisations to gather as much intelligence as possible on militant groups and individuals preparing to come to Ireland on May Day.
The protesters are also expected here in June for the EU-US summit, which will be attended by President George Bush. However, because the Garda does not have powers of preventive detention, it cannot use the intelligence gained to detain people as a means to stop potential trouble.
Laws allowing "known risk" individuals to be turned back at Irish ports and airports do exist, but are only to be used in extreme circumstances and when there is a serious and immediate risk to the public or to property. One Garda source said it was unlikely these laws could be applied to protesters.
Those coming here will make up a loose coalition of groups opposed to war, the EU, the police, globalisation and a range of establishment figures and bodies.
Although details of the massive security operation are still being finalised, sources say that about 4,000 gardaí will be on duty on May Day.
Approximately 1,200 of these will be assigned to public order duties and will be on the front line if protests turn violent.
Garda leave has been cancelled for the May Day weekend.
Soldiers and gardaí have been given special anti-riot training to prepare them in the event of serious civil unrest.
Ten EU accession states will officially become members of the EU on May 1st. The celebrations are taking place here because of Ireland's presidency of the EU.
Heads of state from existing EU states and accession states will be present at ceremonies in Farmleigh House and at Áras an Uachtaráin, both in the Phoenix Park, Dublin. These ceremonies will mark the official entry into the EU of the 10 new states.
Although the cancellation of a special concert in O'Connell Street to mark the day has eased security fears slightly, the move means it may be much harder to predict the precise location of likely trouble spots around Dublin.
Officers have identified a six-hour period on the day, between 4 p.m. and 10 p.m., during which they believe trouble is most likely to occur. The Phoenix Park, which will be closed for the day, will be the subject of the largest security "lock-out" in the history of the State.
However, Irish and international protesters are expected to gather at the entrance to the park at Parkgate Street. The area is a major traffic junction, and its wide streets make it an ideal place for a large crowd to congregate.
Rapid reaction teams of soldiers will be available to erect fences and other barriers in the event that gardaí need them to keep protesters away from trouble spots. Gardaí are expected to use water cannon on the day if needed. Other riot and crowd control mechanisms are also being examined.