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Expert Profile

John Mullen

John Mullen

Principal and Quantum Expert

Extensive lecturing on construction commercial issues both in-house and publicly
Oil & Gas
Process & Industrial
Middle East
United Kingdom


  • Chartered Quantity Surveyor and Chartered Civil Engineering Surveyor
  • Over 40 years of engineering and construction experience
  • Specialist in the evaluation of construction claims
  • Over 70 international expert appointments
  • Appointed on disputes up to $790 million in value
  • Cross examined on many occasions, including over 10 times by specialist Queen’s Counsel
  • Oral tribunal evidence to some of construction’s most eminent judges and arbitrators
  • A Who’s Who Legal Global Thought Leader 2019 and 2020, Thought Leaders Global Elite – Construction Experts 2021


A chartered quantity surveyor and chartered civil engineering surveyor, John has over 40 years’ experience of the construction industry. In that time he has been employed by contractors and professional practices and represented public sector bodies, private sector employers, architects, quantity surveyors, insurers, accountants, contractors, sub-contractors and materials manufacturers.

John trained with a national firm of contractors as a site based quantity surveyor on building and engineering projects, contracted on traditional, cost plus, and management bases, he also worked for local small builders pricing building works.

Over the last 30 years John has specialised in providing consultancy services to the construction industry. This has included pre-contract and post-contract quantity surveying activities, project management, and claims services acting for employers, contractors, subcontractors, insurers, and other construction professionals.

John has worked as expert on building projects up to $790 million, and infrastructure projects up to $760 million, in dispute. He has an international reputation that has led to over 70 appointments as an expert witness, including acting as joint expert. Cross-examined on numerous occasions, including several times by Queen’s Counsel, John’s expert commissions have involved the UK Courts, UNCITRAL, LCIA, ICC, DIAC, ADCAC, AFSA, DIS, and ad hoc Arbitrations. He has given evidence in various areas including aspects of pre and post-contract surveying; the measurement and valuation of work done; variations; termination costs and claims for suspension prolongation; acceleration; and disruption.

John’s main areas of technical specialisation are in dealing with difficult final account and claims issues; valuation issues; variation issues; and claims topics including the financial effects of termination, suspension, delays, prolongation, disruption, acceleration, cost escalation, plant depreciation, preliminaries thickening, overheads, and loss of profit claims.

John is co-author of two industry publications:

  • Evaluating Contract Claims, 3rd edition, Wiley Blackwell, 2019
  • The Expert Witness in Construction. Wiley Blackwell, 2013

WWL says: 

“With over four decades of experience, John Mullen has a stellar reputation in the market for his deep knowledge and vast experience handling high-value construction disputes before an array of arbitral tribunals.”

John Mullen has been recognised by Who’s Who Legal as a Global Leader in Arbitration Expert Witnesses 2023, Construction Expert Witnesses 2023, and in Consulting Experts – Construction – Quantum Delay & Technical 2023.