Chapter 10 on International Atmospheric Trust cases investigates the application of the public trust doctrine in climate litigation. Historically, under this doctrine courts have maintained that certain natural and cultural resources should be held in trust for the public, with the government acting as a trustee. The authors explain the practical application and interpretation of this doctrine in climate litigation, examining key cases (through 2022) across various jurisdictions, including the United States, Canada, India, Pakistan, and Uganda. The effect is to produce a Restatement of best practices in climate litigation revealing the successes and challenges encountered when invoking the public trust doctrine in climate litigation. This review of the case law reveals an emerging distinction between the U.S., which has seen the erection of procedural barriers in federal and state courts to avoid deciding cases on the merits, and international courts, who have reached the merits of several cases, ordering remedial actions. The chapter underscores the potential of this doctrine to induce more robust climate action among the political branches of government, reflecting a growing recognition among courts outside the U.S. of their own role in safeguarding the atmosphere.