The concept of a ‘safe harbour’ has been mentioned in several contexts during ongoing discussions around regulatory developments towards mandatory human rights and environmental due diligence (mHREDD) which continue at international, European and national levels. This article analyses the concept of a ‘safe harbour’ and how it relates to human rights due diligence (HRDD) as described in the UN Guiding Principles on Business and Human Rights (UNGPs). It discusses examples of other types of safe harbours which were recognized in legislation and case law; considers that a safe harbour could result in a ‘tick-box’ approach; highlights the implications for access to remedy; and distinguishes a safe harbour exemption from a defence of having undertaken HRDD in accordance with an expected standard of conduct.