The validity of Model Clauses for EU personal data transfer to the United States is now in real doubt as a result of a new Irish High Court judgment stating that there are “well founded grounds” to find the Model Clauses invalid. The issue of Model Clauses as a legitimate data transfer mechanism will now be adjudicated by the European Court of Justice (ECJ), the same court that previously overturned the Safe Harbor arrangement. EU and US companies will need to consider various strategies in anticipation of this decision.