McClain has been suspended indefinitely without pay for violating the league's policy on substances of abuse. NFL Network Insider Ian Rapoport reported two weeks ago that McClain was facing the suspension due to a missed drug test, per a source informed of the situation.
His previous 10-game suspension ended on Nov. 21 following the conclusion of Week 11. Rapoport reported two weeks ago, however, that the Cowboys were planning to keep McClain on the reserve/did not report list and that the team doubted that McClain would come back to play in the NFL again.
The 27-year-old former first-round pick played the past two seasons in Dallas, following his first three campaigns in Oakland.