You will need to carry out research as to ascertain what duties the legal system has interpreted.

To help this it may be advisable to consider the following:

• Ethical duties of the project manager - usually found in codes of conduct from professional bodies.
• The absence of a professional body - unlike other professions - what problems this may cause?
• Whole area of the law of Negligence/ Construction Liability?
• How are project managers distinct from the other construction related disciplines? What roles do the other construction professionals perform?
• What do project managers actually do?
• What do project managers control?
• Who do project managers work for?
• Case Law (which is limited)

• Starting Pont - Web searches, construction law websites, Legal Firms website particularly though involved in construction