The Constitution (Bunreacht na hÉireann) guarantees your right in Ireland to form associations and unions. You may form any type of association for whatever purpose you choose, whether it is sporting, social, charitable, commercial or political.
This right is limited by legislation to protect public order and morality. For example, associations formed for the purpose of treason or some anti-constitutional or illegal purpose cannot rely on this right to freedom of association.
Your right to freedom of association is set down in Article 40 of the
Constitution. You can view the
full text of the Irish Constitution here.