On June 22, 2012, Višňovský was traded to the New York Islanders for a second round pick in the 2013 NHL Entry Draft. Shortly thereafter, Višňovský filed a grievance through the National Hockey League Players' Association (NHLPA) seeking to void the trade, claiming that the no trade clause in his original contract with Los Angeles was still valid, since he never revoked it when Edmonton traded him to Anaheim.[7] An arbitrator ruled against Višňovský in this case and the trade was upheld
The whole Visnovsky situation can be very confusing, here's what happened:
(1) Visnovsky signed a 5 year contract extension with LA beginning in 2008-2009. The contract included a NTC that was scheduled to go into effect on July 1st, 2008.
(2) LA->EDM: On June 29th, 2008 LA traded Visnovsky to Edmonton, before the NTC went into effect.
(3) EDM->ANA: On March 3rd, 2010 Edmonton traded Visnovsky to Anaheim. Before trading Visnovsky, Edmonton asked if he would waive his NTC for the trade and he agreed to do so.
(4) ANA->NYI: On June 22, 2012 Anaheim traded Visnovsky to the Islanders and Visnovsky later filed a grievance that the Ducks never asked him to waive his NTC.
(5) The arbitrator ruled that Visnovsky no longer had a NTC and lost his grievance.
So who created this whole screwed up situation? Edmonton. When players are traded (2), by default any future NTC/NMC that has not gone into effect is voided (e.g. Subban)--unless the team notifies the NHL, player, and PA in writing that they are honoring the cause (CBA 11.8a). Edmonton also clouded up the fiasco by asking Visnovsky to waive a NTC he no longer had before trading him to Anaheim (3).
After Visnovsky was traded from Anaheim to the Islanders (4) he filed a grievance (5) that his NTC wasn't honored. The arbitrator ruled Edmonton never notified the CBA parties that the team was going to honor the future Visnovsky NTC after the trade from LA (2). No parties at the grievance hearing (NHL, PA, team, player, agent) were able to produce a copy of a notification by Edmonton stating it would honor the future NTC clause that was not yet in effect for Visnovsky at the time of the trade (2).
TL;DR summary: A lot of folks and media mistakenly thought Visnovsky lost his NTC after waiving it for the EDM->ANA trade (3). He actually lost it two years earlier in the LA->EDM trade (2) when Edmonton didn't file the paperwork required by the CBA to keep Visnovsky's future NTC from being voided by the trade. Did Edmonton intend to honor the NTC in the trade and made a mistake not by filing the paperwork? Or did they simply not understand the CBA rules and mistakenly thought Visnovsky still had an NTC when they asked him to waive it? Who knows.