In response, Activision filed a suit seeking a declaration that it was not in violation of the Gibson patent; Activision also asserted that Gibson had given an implied license by waiting to assert the patent and that the patent was invalid.[189] On March 17, 2008, Gibson sued six retailers (GameStop, Amazon.com, Wal-Mart, Target, Toys "R" Us and Kmart) for selling Guitar Hero products.[190][191] Subsequently, on March 21, 2008, Gibson also filed a lawsuit against EA, MTV, and Harmonix over their game Rock Band also for violation of its patent, to which a Harmonix spokesperson stated that Gibson's claims are "completely without merit".[192] Activision lawyer Mary Tuck stated in their legal filings that they believe that Gibson initiated the lawsuit due to the fact that "Activision was not [interested] in renewing the License and Marketing Support Agreement" with Gibson Guitars.[193] In February 2009, the United States District Court for the Central District of California ruled against Gibson in their case against Activision, stating that the controllers are not musical instruments but "toys that represent other items", and that Gibson's patent only covers instruments that send out analog signals.[194][195] Activision and Gibson settled the suit following this ruling.[196]