The team representatives of the NBPA met on Monday and decided to reject the owners' latest offer.
Billy Hunter announced that the NBPA has filed a notice of disclaimer and will file an anti-trust suit against the NBA.
"Although we chose this today, we have not chosen to be in this position," said Derek Fisher. "This is not a strike."
The players reportedly were unanimous in their decision to go forward with decertificaiton.
The owners have said they will terminate all player contracts if the players decertify and that would mean all players effectively become free agents.