Conducting planet-scale mobility experiments and measurements is of great interest to network researchers for building the next generation of wireless networking technologies, or for studying interdisciplinary problems in complex networks. There are many technical challenges that need to be addressed before such experiments can take place. But at the same time, there are many non-technical issues that need to be tackled in order to preserve the welfare of participants in these studies. While some of these issues have been addressed in previous small-scale studies, they become increasingly complex when differences between countries need to be taken into account.This position paper highlights some of these issues and argues that they need to be addressed before planet-scale measurement experiments can be conducted. We discuss ethical, regulatory, cultural and privacy issues, and consider how to design measurement systems that will scale up to planet-wide experiments. We motivate our approach by discussing work in measurement of mobile and online social networks.