On June 20, 2003, the United States patent on the LZW algorithm expired
[3], which means that Unisys and Compuserve can no longer collect royalties for use of the GIF format in that country. Those bothered with the patent enforcement dubbed this day GIF Liberation Day. The equivalent patents in Europe and Japan expired on June 18 and June 20, 2004 respectively, with the Canadian patent following on July 7.