The NFL players' union sent an open letter to team owners calling for an end to the lockout of on-field officials and hinting that it's a violation of the contract between the players and the league.
The players were locked out for 4½ months last year, and they emphasized in the letter, posted Sunday on the union's website, that a lack of a safe working environment exists with replacement officials working the games.
Domonique Foxworth, president of the NFL Players Association, Drew Brees and Scott Fujita are among the union members who signed it.
Replacement officials admitted making two mistakes in Minnesota's victory over San Francisco on Sunday, while several other games included suspect calls that could have affected the outcomes.
Referee Ken Roan said he twice granted 49ers coach Jim Harbaugh challenges after Harbaugh called timeout in the fourth quarter. Neither challenge should have been allowed once Harbaugh asked for time.
In the Lions-Titans and Bengals-Redskins games, officials marched off too much yardage on penalties.
Lions LB Stephen Tulloch's helmet-to-helmet hit on Craig Stevens wound up as a 27-yard penalty, while the Redskins were penalized 20 yards instead of 15 for unsportsmanlike conduct in the final seconds of their loss.
"Your decision to lock out officials with more than 1,500 years of collective NFL experience has led to a deterioration of order, safety and integrity," the NFL Players Association wrote. "This affirmative decision has not only resulted in poor calls, missed calls and bad game management, but the combination of those deficiencies will only continue to jeopardize player health and safety and the integrity of the game that has taken decades to build."
The NFL did not immediately respond to a request for comment.
In the letter signed by 12 current or former players, the players also ask why Commissioner Roger Goodell issues suspensions and fines "in the name of player health and safety" while the regular officials the league entrusts to maintain health and safety are locked out.
"As players, we see this game as more than the 'product' you reference at times," the letter said. "You cannot simply switch to a group of cheaper officials and fulfil your legal, moral, and duty obligations to us and our fans. You need to end the lockout and bring back the officials immediately."
The NFL locked out the officials in June after their contact expired. It has used replacements for the first time since 2001, when the regular officials missed only the first week of action.
But those replacements had experience at the highest levels of college football, and the current replacements come from lower college levels or from other leagues such as Arena Football.
There have been numerous complaints by players and coaches about the officiating — certainly more than when the regular officials work — and one particularly embarrassing episode in which an official was removed from working a New Orleans game because he posted photos of himself in Saints gear on Facebook.
"The removal of the veteran officials from regular-season games left a group of your replacements who have proved to be incapable of keeping pace with the speed of the game," the players wrote. "Coaches and players have complained of numerous errors and failures including: erratic and missed calls on egregious holds and hits, increased skirmishes between players and confusion about game rules. Many replacements have lost control of games due to inexperience and unfamiliarity with players and rules."
Browns linebacker Fujita was suspended for three games by Goodell for his role in the Saints' bounties scandal, a suspension that was temporarily placed on hold by an appeals panel.
Among others signing the letter were Titans quarterback Matt Hasselbeck, Packers centre Jeff Saturday and former star safety Brian Dawkins, now retired.