The NFL Players Associated rejected the proposal, however.
That means Brown would have to remain on the 53-man roster during his rehabilitation. Otherwise, the team would have to place him on injured reserve, ending his season.
Had the proposal passed, the Cardinals and other teams would have received a roster exemption allowing one seriously injured player to return in the second half of the season.
NFL owners had approved the change in May, but they needed NFLPA approval to implement it.
Players injured before training camps opened remain eligible to go on the physically unable to perform (PUP) list, generally returning to the 53-man roster after the first six weeks of the season. The PUP list is not available to players injured once training camps have begun.