Earlier this morning, Bushiroad issued a cease and desist to those responsible for the creation and management of the Cardfight Capital program, a BYOND-based client which allows the user to participate in online cardfights. The program first surfaced in early 2011 as a means of playing in the Japanese format of the Cardfight!! Vanguard Trading Card Game, and predates the existence of the English-language format. While long used by both professionals and amateurs to test decks and practice for upcoming tournaments, with many pros finding their start there, the program itself has always been in violation of copyright laws.
Public opinion is divided on the matter. For many people, Cardfight Capital is their only means to play the game. However, the game could hurt the sales of the upcoming Ride to Victory! 3DS game, which among fans is considered likely to see an English-language release despite the lack of official confirmation. The shutting down of Cardfight Capital would make it more difficult both for amateurs to develop their skills to enter into the pro scene, and hurt the pros' ability to analyze and test upcoming decks. However, this would also lead to more box sales due to players being required to play with real cards rather than test online, and if Bushiroad does not defend their license at this point, they may stand to lose their ability to defend it in the future.
Cardfight Capital was created by Devourer of Souls, and has been run continuously since March of 2011. While other programs like Vanguard Master and Cray Online have surfaced in the past, none have reached the same level of usership as CFC. Much as with the similarly-controversial restricted list, within 24 hours of the news breaking, a petition against Bushiroad's decision has surfaced.
Update 9:00 PM EST: The possibility has come up that the cease and desist is a hoax, and the Bushiroad email address used by the alleged legal representative was seized through fraudulent means. None of this has been confirmed as of yet.
Update 1/6/13 12:42 PM EST: The main sever of CFC has been closed down. As of now, only private hosting remains, and the game will not be updated.
Followup 1/11/13 9:31 AM EST