Various Privileges
Sacerdotal Privilege
So-called sacerdotal privilege is not recognised at common law in England, but  has been recognised on a limited basis in Ireland. Sacerdotal privilege  has been recognised in the United States. Under Catholic/Roman Catholic Church practice, a priest hearing  confession is subject to an absolute vow of confidentiality. The Catholic Church holds that the confession of sins is necessary for redemption.
The principle was recognised in Ireland in the 1940s to attach to information given in confidence to a priest outside of the confessional.
Sacerdotal privilege is controversial. It is not clear to what extent it applies to less well recognised religion. 2012 legislation makes it an offence for a person who has information regarding certain offences against children and vulnerable persons to withhold the information. It was provided that the obligation was without prejudice to any privilege that may arise in any criminal proceedings.
Against Self-Incrimination
The privilege against self-incrimination is a thread which runs through much of criminal procedure. It is recognised by the Constitution and by the European Convention on Human Rights. The principle is reflected in statutory provisions, common law and practice.  It has multiple facets.
In broad terms, it involves immunity from being compelled on threat of penal punishment to answer question posed by persons or bodies in authority.
- an immunity from being compelled on threat of punishment or sancation, to answer questions, which may incriminate him:
- an immunity for persons under suspicion of criminal responsibility whilst being interviewed by the police officers and persons in other similar positions of authority from being compelled threat of  penalty/ punishment punishment to answer questions of any kind;
- an immunity for accused persons undergoing trial from being compelled to give evidence or answer questions put to them;
- an immunity for persons who have been charged with a criminal offence from having questions material to the offence addressed to them by police officers or persons in possession of authority;
- an immunity at least in some cases for accused persons undergoing trial from having adverse comment made by reason of the failure to answer questions or give evidence of trial.
The principle has been diluted to some extent. See the chapters on criminal procedure.
Human Rights Protection
The privilege is recognised specifically by in human rights instruments worldwide and under the United States Constitution.
The European Convention on Human Rights has distinguished between real evidence and testimonial evidence. Accordingly, DNA, fingerprinting and other such evidence does not attract the right to remain silent. It is evidence independent of the will of the accused.
There is controversy as to the extent to which the right implies protection from compulsion. See separate chapters in relation to the protections in relation to  taking of fingerprints, various samples etc.
Informer’s Identity
There is a long-standing common law privilege against disclosure of the identity of informers. The rationale is based on the public interest in protecting persons who assist the police with detection of crime. More practically, this may be necessary for the protection of their lives and safety.
The privilege affects the identity of the informer. It is unclear as to what extent it protects the content of the information given. The disclosure of information and other evidence which risks the disclosure of the informer’s identity is likely to be privileged.
An exception is allowed where disclosing the identity of the informer would establish the accused’s innocence. On a wider view, disclosure may be allowed where it is required to do justice.
Disclosure to Whom
The tendency of the Court is to uphold the confidentiality and anonymity of informers An informer is a person who discloses breaches of the law to the authorities.  It applies principally to disclosure to police, but also extends to disclosures to other public officers and persons in authority. The privilege applies to information given to prison authorities and other regulatory and enforcement bodies established by statute in particular spheres.
The Courts distinguish between classes of bodies to whom the privilege attaches. Privilege has been held to apply in respect of the Director of Consumer Affairs, the predecessor of National Consumers Agency in the context of enforcement of its function. In contrast, it has not been allowed in respect of a complaint to the Law Society in its capacity as regulator of solicitors.
The Protection for Persons Reporting Child Abuse Act 1998 gives immunity from civil liability for persons making child sexual abuse allegations subject to certain conditions. The person must act reasonably and in good faith.
The courts have considered whether the privilege might extend to disclosures made to Members of Parliament in respect of alleged wrongdoing. The  Supreme Court has rejected the notion that the information disclosed outside of  Parliament is protected by parliamentary privilege.
Some element of discretion might be exercised in relation to confidential disclosures to Teactai Dala. There is no absolute  privilege for such disclosures and it may be compelled where the interests of justice so require such as where it is relevant to guilt or innocence.
The Courts have considered disclosures to some authorities in the context of public interest privilege. This is not absolute and yields to the interest of justice, in particular cases.
Journalists
Traditionally, journalistic sources did not enjoy privilege. Famously, an RTE journalist Kevin O’Kelly was committed to prison for failure to disclose details of subversive interviewees. The courts have come to accept in later cases that the anonymity of journalist sources should be set aside  only where it is critical and as a last resort.
The Supreme Court having regard to the freedom of expression in the European Convention on Human Rights has recognised a possible privilege in respect of journalist sources. The possible privilege was recognised in 2010 by the Supreme Court in a case involving the Mahon Tribunal.
Most cases involving informer privilege involve disclosure of wrongdoing to a Garda SÃochána. If the disclosure of identity is critical to innocence, the principle that the identity of the informer might be disclosed if it is necessary in the interest of justice appears to be recognised. Where innocence is at stake, the Courts may lift the privilege.
Innocence at Stake
Constitutional considerations and human rights principles have arisen in the context of the balance between the interest in protecting police informants  and the interest in fairness of trial.
Antiterrorism legislation dating back to 1939 allows for  conviction on terrorist offences, based on evidence of membership of a legal organisation to be offered by way of the opinion of a senior Garda officer. This opinion may be based on informer evidence and will generally be protected from cross-examination as to the identity of the source. The Courts have accepted that the restrictions in cross-examination are necessary to uphold informer privilege in this context and does not prejudice a fair trial.
The use of evidence based on a senior Garda’s belief as a basis of conviction generally under anti-terrorism legislation and now under so-called anti-gangland legislation has been challenged on the basis of incompatibility with the right to a fair trial in the European Convention on Human Rights.
The Court may require that the basis of the evidence be disclosed in private to it in camera to the Court.
The DPP has indicated that it would not prosecute offences resting only on belief of a senior officer. Its practice is not to prosecute unless other corroborative evidence exists. Cross-examination may be allowed in respect of every other issue, and up to the point of disclosure of the identity of the source. Belief may be challenged in other respects. Usually the belief will be based on a variety of sources.
Innocence at Stake
It is argued that there is an exception to the legal personal privilege if the question of a person’s innocence is at stake. It has been suggested that if there were documents in the possession or control of a solicitor or a third-party, which would help to further the defence of an accused, then no privilege should attach. It is based on the principle that privilege should not operate to deny evidence to a jury that might otherwise acquit the accused.
Different views have been taken on the proposition. Some Courts have supported it. Higher Courts however have reiterated that legal professional privilege in contrast to public interest immunity is not subject to any balancing consideration. Irish Courts may not follow the more absolute view.