In the new wave of international investment treaties, investor protections are under scrutiny as states seek to ‘restore’ their right to regulate. The umbrella clause is one investor protection under reconsideration. The perception, held by some, is that the umbrella clause permits an ‘unjustified intrusion’ into a state’s right to regulate within its territory. For that reason, the clause is increasingly being omitted from modern-day treaties. This article undertakes a detailed analysis of the umbrella clause and its divergent construction by investment treaty tribunals. It focuses on four particular complexities associated with the umbrella clause that have confronted tribunals to date. In conducting this analysis, the author seeks to demonstrate that, properly construed, the umbrella clause does not have far-reaching ramifications or interfere with a state’s right to regulate. It has an important place in the new wave of international investment treaties but should be carefully drafted. A suggested formulation, which has in mind the four complexities discussed, is offered up.