Halloween, or Samhain, originated with the Druids, who celebrated the end of the harvest season and the Celtic new year with parties and bonfires. However, one's choice of costume could, in theory, land a Halloween reveller in jail.
The Fianna Fail TD, Ms Mary Hanafin, said that although no one can be prosecuted for witchcraft or sorcery, anyone pretending to be a witch is still governed by 260-year-old laws.
This means the trick-or-treater standing at your door in fancy dress over the next few nights could, in theory, face prosecution and be jailed without bail for a year. The Government is working to update these "outdated and ancient" laws, she said.
Local celebrations of Halloween started yesterday with an Amnesty International party at Meeting House Square in Temple Bar, Dublin.
Local children as well as some from Nigeria, Angola, Japan and France were invited to sign the Universal Declaration of Human Rights, which declares equality in dignity and rights for all human beings. A face painter, musician and storyteller were there to entertain the children, who were also given bags of sweets.
Dublin's fourth Halloween parade, organised by Samhain '98, begins tonight at 7 o'clock at Parnell Square. Last year 5,000 people participated in the event which will end at the Civic Offices with a pyrotechnic display by Theatre of Fire.
Parents should make sure their children don't frighten older people during the Halloween festivities, Mr Sean Ryan, Labour's spokesman on older people's issues, warned.
"The winter months can be very intimidating for older people. Halloween can spell greater fears for them, with children knocking on their doors, bangers exploding and fireworks blasting outside their windows."
Mr Ryan said parents should accompany children when "trick or treating" and should visit older people in the early part of the evening.