About Mark Tottenham
Barrister. Author. Speaker. Leading authority on Expert Evidence.
Mark Tottenham is an Irish barrister, author, publisher and podcaster with more than 20 years’ experience in legal practice. He is the author of The Reliable Expert Witness and lead author of the award-winning A Guide to Expert Witness Evidence.
He is also the founder of Decisis Law Reports, Training Consultant to The Expert Witness Site and co-host of the award-winning legal podcast The Fifth Court. Across these roles, his work helps to make complex legal issues clearer, more practical and more accessible.
Expert Evidence
“An expert on experts.”
- Baroness Sue Black, forensic anthropologist.
Mark is the author of The Reliable Expert Witness, a practical guide to preparing reports, giving evidence and meeting the responsibilities of a professional witness.
He was lead author of A Guide to Expert Witness Evidence, published by Bloomsbury Professional and named DSBA Practical Law Book of the Year in 2020. A substantially updated second edition is due to be published in late 2026.
As Training Consultant to The Expert Witness Site, Mark contributes to professional training for expert witnesses. He advises experts and legal teams on issues including independence, methodology, report writing and the presentation of evidence.
Mark regularly addresses lawyers, expert witnesses and other professionals. He has spoken at conferences in Ireland, the United Kingdom, Germany and the United States, and has delivered online presentations to audiences elsewhere in Europe and in Singapore.
Decisis Law Reports
Mark founded Decisis Law Reports in 2011. Decisis is an online encyclopaedia and index of Irish case law.
Used by judges, barristers, solicitors, government departments, public bodies and universities, Decisis provides concise reports of judgments from the Supreme Court, Court of Appeal and High Court.
With more than 17,000 reports, Decisis is one of the most extensive collections of Irish case reports ever published.
The Fifth Court
Mark co-hosts The Fifth Court, an award-winning Irish legal podcast, with fellow barrister Peter Leonard BL.
Guests have included Jimmy Wales, Mary McAleese, Frank Clarke, Sir Geoffrey Vos, Georg Kodek, Verona Murphy and Peter Kelly.
The podcast has presented live events at Electric Picnic, Kilkenomics, the Allingham Arts Festival and the Law Society’s Future of Legal Practice Summit. It also received the Dublin Solicitors Bar Association’s Outstanding Legal Podcast award in 2024.
Speaker, Trainer and Commentator
Mark’s principal speaking topics include:
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Expert evidence and the responsibilities of expert witnesses
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Independence, credibility and failures in expert evidence
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The preparation and presentation of expert reports
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Historical cases involving expert witnesses and miscarriages of justice
He is available for keynote presentations, conferences, professional training, specialist seminars, consultancy and media commentary.
He has also delivered lectures and presentations on expert evidence to: the Family Lawyers Association of Ireland; the Chief State Solicitors Office; Probate Bar Association; the Association of Consulting Forensic Engineers; the Bar of Ireland; the Solicitors Growth Network; the Counterfeit Experts Group (European Central Bank); the Society of Construction Law; the Asia Pacific Institute of Experts (APIEX) (Singapore); the International Protection Appeals Tribunal; the Chartered Institute of Arbitrators (Irish Branch); the Tort and Insurance Bar of Ireland; La Touche Training; CPD Philanthropy; the Law Society of Ireland; the Honorable Society of the Kings Inns; Fair Trials Europe; The German Irish Law and Business Association (GILBA); and the Lexangle Expert Witness Conference in Washington DC.
He is available for keynote presentations, conferences, professional training, specialist seminars, consultancy and media commentary.
To discuss a speaking, training or consultancy engagement, please contact Mark.
Property & Probate Law
Alongside his work in expert evidence, Mark practises as a barrister in property and probate law, with particular experience in conveyancing and property matters, landlord and tenant law, trusts and probate disputes. He is also an experienced mediator, particularly in property and probate disputes.