The roots of the Patent Cooperation Treaty (PCT) go back to 1966, when the Executive Committee of the Paris Convention for the Protection of Industrial Property called for a study of how to reduce, for applicants and patent offices, the duplication of effort involved in filing and obtaining patent applications for the same invention in different countries. The resulting WIPO treaty, the PCT, was signed in Washington, D.C., in 1970 and entered into force in 1978. The treaty was amended in 1979, 1984, 2001, and 2004. As of September 15, 2005, there were 128 Contracting Parties to the PCT.