The suit was filed in federal court in New York after a unanimous vote of the five club executives who make up the executive committee of NFL Properties, the league's marketing arm.
In a move that clearly escalates the feud between the NFL and Cowboy owner Jerry Jones, the lawsuit seeks to prevent the Cowboys, Jones and Texas Stadium from further damaging NFL Properties.
The NFL wants the court to order the defendants to stop violating their agreements with NFL Properties regarding club marks and logos, and prevent the defendants from signing any additional deals that undermine existing NFL sponsorship or licensing contracts.
"The Cowboys have made it clear through their recent actions and statements that they want to change the basic manner in which NFL Properties does business," said Roger Headrick, executive committee chairman of NFL Properties.
An MRI test revealed that Lachey, a three-time Pro Bowl selection and anchor of the 1991 line that helped Washington win the Super Bowl, sustained a complete tear of the rotator cuff in his right shoulder on the Redskins' first offensive series.
His shoulders sagging, Lachey was resigned to sitting out the rest of the season after learning the news.
The Redskins want him to see a couple of shoulder specialists--who will likely recommend surgery--but Lachey first wanted to go home Monday night and discuss his football future with his wife.
"I think you have to face that question when you've had a knee injury in your ninth year and a shoulder injury in your 11th," Lachey said. "You have to figure out if you're able to come back, and if you do come back, are you the same player as before? I don't want to cripple myself playing this game."
Erik Williams, the Dallas Cowboys' starting offensive tackle, will sit out the next two or three weeks because of a strained left calf muscle sustained in Sunday night's 23-17 victory over Minnesota.
Coach Barry Switzer said Ron Stone will practice at right tackle this week and "probably start against Arizona."
Williams hurt his right knee in a car accident last October.
"Erik has been wearing a brace on the leg and I think he's been trying to compensate by putting a lot of weight on the left leg," Switzer said. "I guess something had to give."
While the Cowboys lost Williams for the rest of September, they gained some depth when offensive lineman Derek Kennard came back to the team. Kennard walked out of training camp, saying he had decided to retire from football.
With veteran quarterbacks Frank Reich and Jack Trudeau struggling and the expansion Carolina Panthers off to an 0-3 start, Coach Dom Capers announced that it was time to reopen the competition, this time with top draft pick Kerry Collins included.
"All three guys are in the mix," Capers said.
Capers, whose team doesn't play again until its Oct. 1 home game against Tampa Bay, said he had planned to give Collins a large amount of work in practice during the bye week. Now, Collins will get even more work, as will several of the Panthers' other young players, Capers said.