The security of mobile communications is becoming increasingly critical, prompting security researchers to focus their attention on vulnerabilities in cellular systems. Researchers need to fully understand the legal ramifications of interacting with specialized hardware, cellular communications, and the restrictions imposed by service providers. This briefing will provide a legal overview of what a researcher should keep in mind when investigating mobile communications, technologies, and networks. We will cover legal issues raised by end user license agreements, jailrooting or rooting devices, and intercepting communications.