The Cowboys owner reportedly wanted his players to see the business side of football, and how protesting during the anthem could affect TV ratings and sponsors.
While the Cowboys already have a team policy in place regarding the anthem, Goodell's letter suggested a new rule, similar to the NBA's requirement for its players to stand for the anthem, could be enacted after discussing the matter at the fall meetings on October 17 and 18.
In the two games since, the players have stood on the sideline with no one kneeling. This comes after Dallas Cowboys owner Jerry Jones said he would bench anyone who shows disrespect to the American flag. "I've got my morals".
"This is a workplace issue", Jones said.
Wade Rathke, chief organizer of Local 100, said that Jones' threat violates the National Labor Relations Act of 1935, which allows employees "to engage in protected concerted activities for the goal of collective bargaining or other mutual aid or protection".
ESPN's Josina Anderson tweeted out quotes from one anonymous player who seems apoplectic.
"We can not in anyway give the implication that we tolerate disrespecting the flag", Jones said, according to the Morning News.
But those political motives of kneeling likely would not protect the players from discipline.
"That is clearly a term and condition of employment", Cawyer said. Employment law allows private sector employers great latitude in restricting employee conduct and speech while at work. I don't want to cause no attention to nobody else and bring unwanted attention, but on the same token, you know, there's certain things that people are doing it for.
Paul Secunda, director, labor and employment law program, Marquette University: "I've heard a lot of fans talk about Constitutional rights".
"If the government pays for the patriotic display and the firing is a result of the behavior being deemed insufficiently patriotic, it is conceivable that that a claim could then be articulated", said Floyd Abrams, a First Amendment attorney in NY.