What does it happen if as a result, among others, of an alleged State’s failure to enforce its environmental regulation, a foreign investor suffers significant losses due to the environmental deterioration provoked by the failure, argues that the failure constitutes a violation of its rights under an international investment agreement, and requests compensation from the host State? The award in Peter A. Allard v the Government of Barbados answers this and other related questions. (Peter A. Allard v the Government of Barbados, Permanent Court of Arbitration, PCA Case No 2012-06, 27 June 2016) (Allard v Barbados). Although the investor lost the case, there are lessons to draw for environmental authorities and for New Zealand investors abroad.