An American company called Tune Hunter says Shazam and a number of other companies have infringed its patent (first filed in 2000). Samsung, Apple, Shazam, Amazon, Napster, Motorola, Gracenote, Cellco, LG, AT&T and Pantech have all been named in legal action that seeks damages and an injunction. The patent awarded to Tune Hunter in 2005 "relates to a music identification/purchasing system, specifically to a method for marking the time and the name of the radio station in portable device such as a key holder, watch, cellular phone, beeper or the like which will allow the user to learn via internet or regular telephone the name of the song, artist and/or music company by matching the stored data with broadcast archive."
Shazam, which was founded in 2002, has 35 million users worldwide and identifies a million music tracks every day. [Sources: USPTO.gov; cnet.com; RFCexpress.com]