Prior art has to pre-date the filing date[1]. And even if they did have prior art, proving so in court could be expensive if the patent holder decides to pursue

Prior art has to pre-date the filing date[1]. And even if they did have prior art, proving so in court could be expensive if the patent holder decides to pursue it. [1] http://www.iusmentis.com/patents/priorart/ http://www.iusmentis.com/patents/priorart/