Patent law is one of the few areas of law recognized as a specialty. Though attorneys in other areas of law may limit their practices to a particular field (such as real estate law, family law, etc.), those practice areas are generally not recognized as specialties. Under ethical rules governing attorney conduct in most states, patent attorneys may hold themselves out to the public as specialists. Patent attorneys usually are registered to practice before the United States Patent and Trademark Office (USPTO). This registration allows the attorney to file and prosecute patent applications before the USPTO on behalf of clients. Patent attorneys may also litigate patent infringement, patent validity and/or patent enforceability disputes in court. Patent litigations are generally federal court cases. Patent attorneys may also typically prepare and negotiate patent licenses or other contracts involving patent rights, perform patent due diligence investigations, analyze patent portfolios, give advice for developing patenting programs, and/or prepare patent infringement and/or patent validity analyzes and opinions.