A Checklist of legal requirements and key issues concerning foreign filing restrictions at the US Patent and Trademark Office (USPTO) and foreign patent offices. This Checklist identifies and compares foreign filing restrictions in the US and foreign countries to assist US patent counsel in determining which countries' foreign filing restrictions may apply to an invention. It also identifies tasks for US patent counsel to complete, such as evaluating the nature of the invention, its inventorship, where the invention was made, and the inventors' residencies and nationalities. This Checklist does not address the applicability of technology export control laws.