This article presents the new German law on advance directives from 1 September 2009. The history of the parliamentary process of this law is described, the present regulations are explained, their relevance for medical practice discussed and shortcomings are identified. Finally, the new law is compared with other regulations in the international context. Previously established legal practice in Germany has now become largely confirmed by the new law: An advanced directive must be respected in any decision concerning medical treatment, regardless of the stage of the illness. It can be informally revoked at any time, even with limited decision-making capacity. Nobody may be obliged to issue a directive in any way. Advance directives do not need notarisation or routine updating after certain time intervals. Provided that the patient, who is no longer mentally competent, has issued a lasting power of attorney (Bevollmachtiger), or provided that the patient has been appointed a healthcare proxy by the courts (Betreuer), this authorised surrogate must assert the patient's will. The role of the guardianship court is clarified: it only needs to be involved in cases of disagreement as to the patient's will. The new German law thus combines more legal certainty with a liberal emphasis on patient autonomy and flexible, adaptable regulations.