The EU Clinical Trials Regulation must be implemented directly into the law in the EU Member States, whilst Directives, such as the EU Clinical Trials Directive (CTD), must be incorporated into legislation using national processes, affording an opportunity for Member States to introduce modifications. Dr Harris W. Dalrymple, PRA Health Sciences, writes that this may be one of the reasons that the CTD did not fully achieve its objective of harmonising clinical trial requirements in Europe.