The recent High Court disclosures on Ansbacher are likely to present the prosecuting authorities with intriguing tactical choices: what charges, against whom, and in what sequence should they bring them?

The focus must be to ensure that the evidence is admissible and that the necessary trial witnesses are compellable. On the information available to date, the offences disclosed as most likely to be capable of prosecution are:

Revenue offences.

Offences under exchange control legislation.

Possible perjury.

Breaches of the tax amnesty legislation.

Conspiracy to commit the above or any of the common law offences of aiding, abetting or assisting, or attempts to commit the above.

Charges of "knowingly or wilfully" delivering any "incorrect return, statement or accounts or . . . any incorrect information in connection with any tax" represent perhaps the best prospect of successful criminal prosecutions; the maximum criminal penalties on indictment being fines of up to £10,000 and/or five years' imprisonment.

Where underpayment of tax is due to "fraud or neglect" a convicted person will also face irresistible demands for full repayment plus a whopping penal interest of 2 per cent for each month from October of the relevant tax year.

Assessment for tax and penalties is independent of criminal charges and separate charges will lie where an offence committed by a body corporate is shown to have been committed with the "consent or connivance of any . . . director, manager, secretary are other officer of . . . or member of the committee of management or other controlling authority of the body corporate".

The period for institution of such criminal proceedings is "10 years from the date of the commission of the offence or incurring of the penalty, as the case may be".

On balance, it seems unlikely that any criminal charges for breaches of the exchange control legislation, which was allowed to expire on December 31st, 1992, in preparation for the European single market, could justifiably be preferred in 1999. In this e-commerce age, resurrection of such anachronistic criminal provisions, with a maximum sentence of a £5,000 fine and/or one year's imprisonment, might perhaps also send the wrong message abroad.

Contravention of the tax amnesty prescriptions may carry higher maximum prison sentences of up to eight years. In general, the lesser offences of aiding and abetting, counselling or procuring, and the like, will only be solely or separately charged for good reason.

Under Irish law, the DPP is the sole prosecuting authority empowered to prefer charges on indictment before judge and jury. No prosecution will be initiated unless the evidence collected shows a fair or reasonable prospect of securing a conviction to the criminal, and not merely civil, burden of proof, i.e. beyond all reasonable doubt.

Notoriously, inquiries in recent times by tribunals or Companies Acts inspectors into suspected irregularities in established businesses have been interrupted at various stages by excursions to the High Court for judicial review to challenge the procedures adopted, with mixed results.

In the recent NIB case the Supreme Court clarified that answers to questions properly put by inspectors appointed under the Companies Acts could not be refused on a plea against self-incrimination.

The DPP may give priority to those cases in which the prosecution evidence might be presented with the clearest narrative ease due to a concision of oral testimony and documentary evidence. For the DPP, the easiest cases to prosecute are where the accused has made and signed a confession not otherwise inadmissible according to law.

The tax domicile and present whereabouts of any suspect or witness will be important. The preferred method of investigation of offences of financial irregularity is for detectives to arrest and detain the suspect for a period of six or 12 hours and hear what he/she has to say.

Such arrest and interview procedures will not be available outside Ireland. There may be some prospect of judicial evidence being taken in limited foreign jurisdictions under the European Convention on Mutual Assistance, but the procedures are cumbersome and require separate initiation for each individual prosecution.

Extradition, incidentally, is not available for revenue offences. Indeed, even if a suspect was extradited to Ireland to face charges on non-revenue offences, he/she could not thereafter be prosecuted for revenue offences preferred before or after arrival here.

A difficulty for investigating gardai will be the likely unwillingness of prospective witnesses within the jurisdiction to volunteer statements of evidence. An accused is entitled to written notice of all prosecution statements before any return for trial can be made. The Companies Acts inspectors may only force answers pertaining to the affairs of the company under investigation.

But, even where the replies are material to somebody's guilt, those forced to answer and later subpoenaed to the criminal jury trial could be regarded as "hostile" witnesses.

Other traditional difficulties of documentary proofs have been considerably eased by the Criminal Evidence Act, 1992, by which documentary evidence is now not rendered inadmissible on production of any copy (rather than its original) document at trial.

This amendment has already been of practical usefulness and may be vital in rendering admissible banking and other corporate records which are repeatedly converted from electronic to hard copy and back. Where a clear narrative pattern can be put before the jury with good circumstantial documentation, leading inexorably to an inference of guilt, there may be a fair prospect of securing a conviction beyond all reasonable doubt.

It is usual for defence representatives to deride the prosecution case where the evidence is said to be "entirely circumstantial". The experience of lawyers, however, mirrors that of detectives: it is no criticism of a case that the admissible evidence is wholly circumstantial. Sometimes it is the best evidence.

The recent string of high-profile acquittals suffered by the Serious Fraud Office in England and Wales shows that careful case selection - having regard to just some of the criteria outlined here - will be necessary and timely.

Eanna Mulloy is a practising barrister