Patent attorneys must also be admitted to the practice of law in at least one state or territory of the U.S. or in the District of Columbia. Since patent attorneys are admitted to practice law in a state or territory, they can additionally provide legal services outside the Patent Office if practicing within the jurisdiction they are admitted to practice or if the law of the jurisdiction otherwise permits them to practice although not admitted in that jurisdiction. These legal services include advising a client on matters relating to the licensing of the invention; whether to appeal a decision by the Patent Office to a court; whether to sue for infringement; whether someone is infringing upon the claims of a client's issued patent; and conversely, whether a client is infringing the claims of someone else's issued patent. Patent agents cannot provide legal services of this nature, nor can they represent clients before the Trademark Office part of the USPTO.