Both in the United States and in Europe, the patent laws contain a so-called Bolar provision, which provides safe harbor from patent infringement for certain activities related to obtaining marketing authorization for a drug product, whether it is a small molecule or a biologic drug. Recent court decisions and legislative initiatives on both sides of the Atlantic affect the drug safe harbor and invite a critical analysis of the Bolar provisions in the various jurisdictions.The safe harbor provision in the US differs significantly in scope from the safe harbor provision in the relevant EU Directive, and the national implementations of the EU Directive in individual member countries of the EU again differ significantly from each other. Main differences relate to the question whether the safe harbor extends to activities related to obtaining marketing approval for a new innovative drug, for a medical device, or for a drug outside of the respective jurisdiction, or to post-marketing approval activities. Unresolved questions regarding the scope of the Bolar provisions remain, and there seem to be distinct, in part opposing, trends. The recent Agreement on a Unified Patent Court (UPC) adds additional complexity to the drug safe harbor in the EU.The discussed issues affect drug or medical device companiesâ decisions on aspects of patent infringement litigation strategy and the best location for pre- and post-marketing approval activities. Differences relating to safe harbor for post-marketing approval manufacturing and testing are of particular relevance for the emerging biosimilars industry. [ABSTRACT FROM AUTHOR]