Over the years, the importance of open standards has been acknowledged in EU and national policies. Formal (e.g., ISO) standards are often referred to in software development and procurement. Use of formal (ISO) standards and to what extent ISO standards can be implemented in open source software is considered, with particular reference to patent licensing. It is shown that not all formal standards are open standards and that FRAND commitments may impose major challenges for use of such standards. Further policies and procedures set by standards setting organisations (SSOs) regarding the notification of standards-essential patents (SEPs) present challenges for organisations wishing to implement standards in software. This chapter elaborates implications and suggests ways of addressing the challenges identified. Use of formal standards may create barriers for implementation in open source software and inhibit an open and inclusive business-friendly ecosystem.