If you make a confession to the Gardai, that confession can potentially be used in your trial as evidence against you.
A voluntary confession is a confession that has not been coerced or forced from you and has been made with your true and free will.
If you make a confession that is not voluntary, it cannot be admitted as evidence against you in your trial.
Even if a confession was given voluntarily, it may still be inadmissible because of the oppressive or unfair circumstances in which it was obtained.
A confession will be considered by a court to be involuntary if it was obtained by physical or psychological pressures or by threats or promises made by persons in authority. Threats or promises, which create fear or hope, may take away your free will. Therefore, a confession made as a result of a threat or a promise made by a person in authority is not a voluntary statement.
A confession will also be considered to be involuntary if it was obtained by the use of drugs, hypnosis, alcohol, long-drawn-out interrogation, excessive questioning or any method that takes away your rational intellect or free will.
Basic standards of fairness must be met. For example, if you make a confession after successive bouts of questioning and without having obtained adequate sleep and rest, a court may consider the statement inadmissible.