Prosecution history estoppel, also known as file-wrapper estoppel, is a term used to indicate that a person who has filed a patent application, and then makes narrowing amendments to the application to accommodate the patent law, may be precluded from invoking the doctrine of equivalents to broaden the scope of their claims to cover subject matter ceded by the amendments. Although primarily a U.S. term, questions of whether, or the extent to which the prosecution history should be relevant for determining the extent of protection of a patent also arise outside the U.S. Canada On December 13, 2018, new section 53.1 of the Patent Act makes prosecution history evidence admissible before the Court for the purposes of claim construction. Patents in Canada are subject to a purposive construction, which relies on reading both the claims and the specifications to determine the scope of a patent, and extrinsic evidence is not permitted. Therefore, the Canadian courts emphatically reject what they refer to as "file wrapper estoppel". No distinction is drawn between cases involving allegations of literal infringement and those involving substantive infringement, which means that the negotiations that have taken place between the patentee and the Patent Office cannot be used in order to establish a particular equivalent. Similarly, a patentee is barred from using any previous negotiations with the Patent Office in order to determine the scope of the claims of the patent (i.e. the negotiations cannot be used by the patentee or against the patentee in determining the scope of the claims within the patent). This is one of the significant differences that exist between Canadian and US patent jurisprudence, which leads some legal commentators to state that Canada is more friendly for rights holders in pursuing patent claims. Germany The German Federal Court of Justice ruled in 2002 that "issues derived from prosecution history cannot be taken into account in the assessment of the scope of protection of a patent, even with regard to the requirement of legal certainty". More than a decade later, the Federal Court of Justice ruled on 14 June 2016 that statements made during prosecution may indicate how the skilled person construes a patent. At the same time, the Federal Court of Justice set forth that such indications must not readily be relied on as the sole basis of claim construction. Ireland The Irish Supreme Court has ruled that "evidence from the file which