The protection of a trade mark with a reputation in the European Union law and of a famous trade mark in the US federal law is broader than that granted to ordinary trade marks. The scope of protection of marks with a reputation and famous mark indicates that the principle of speciality is enforced in the federal US law to a larger extent than in the EU law and, in turn, in some Member States of the European Union, in particular Poland. Arguably, this difference results from the differences between the definition of a trade mark with a reputation, used in the European Union, and a famous mark, used the United States. The main difference in US law is that the fame of a mark is defined globally with respect to the general consuming public of the United States, whereas the Court of Justice has indicated that in the European Union whether a trade mark has a reputation is assessed by reference to a significant part of the public concerned with the products or services covered by the specification. Thus, in the EU law, the reputation of a trade mark may be perceived with respect to a narrow group of the public, for example specialists in a given field.