In order to arrest you, the Garda Siochana must have a warrant for your arrest unless you are arrested for an offence that is punishable by imprisonment for a term of 5 years or more. In that case, the Gardai must have reasonable cause to suspect that you are guilty of an offence.
Once you are arrested, you must be brought to a Garda station without undue delay. You must be told the reason for your arrest.
The Gardaí do not have to inform you in any particular form the reason and legal basis for your arrest. However, you do have to be informed in an understandable way why you are being arrested. For example, if you are arrested for drink driving the Garda is not obliged to cite the specific provision ("I am arresting you under the provisions of Section 49 (8) of the Road Traffic Act, 1961"). The courts have recognised flexibility with respect to citation of specific provisions so long as the gist of the provision was explained to the accused by the Garda ("I am arresting you for drink driving").
Your arrest is unlawful if the Garda fails to inform you in ordinary language the reason for your arrest or fails to cite the relevant law. If this happens the detention which follows is unlawful. If your arrest is just a sham or a cover so that you can be questioned in relation to other offences, then that arrest is unlawful. However, if the reasons for your arrest are given to you at any time during your detention, your custody becomes lawful from that point on.
When you are arrested, you have a right to be brought before a court at the first possible opportunity. Different legislation specifies how long you may be held in detention for questioning. In most cases where you have been arrested for an offence punishable by 5 years imprisonment or more, the maximum period of detention is 24 hours.
While you are in detention, you have a constitutional right of reasonable access to a lawyer. You have no constitutional right to be told that you have a right to see a lawyer nor do you have a right have your lawyer in the room with you while you are being interviewed by the police.
If you have been unlawfully arrested, evidence obtained as a result of that arrest will be inadmissible. For example, if you were mistakenly told by a Garda that you were being arrested under the wrong section of the Road Traffic Act, the arrest and the blood sample taken would be unlawful. The blood sample would not be admissible as evidence.
Evidence obtained while you are unlawfully detained has also been unlawfully obtained and will be inadmissible. For example, if you have been in custody for longer than the maximum period allowed and you make a confession, that confession will not be admissible in evidence against you.
Evidence obtained in breach of your right to reasonable access to a lawyer is also inadmissible as evidence against you. For example, if you request a lawyer and your request is refused, any statements you make to the police will be inadmissible as evidence against you.
If you have a question relating to this topic you can contact the Citizens Information Phone Service on 0761 07 4000 (Monday to Friday, 9am to 8pm) or you can visit your local Citizens Information Centre.