The lawyer, Mark Geragos, is representing Kaepernick in the former quarterback's grievance against NFL owners, which claims they colluded against him to keep him out of the league because of his protest of kneeling during the national anthem before games.
Kaepernick was the first NFL player to protest police violence and racial injustice by refusing to stand for the National Anthem in 2016.
Owners had spent months deliberating how to handle the on-field demonstrations after Trump said previous year that players who kneel during the anthem should be punished.
"Lockhart apparently sealed his fate by engaging the President after the notorious Alabama "get that son of a bitch off the field" comment, calling the President's comments "divisive" and making a snarky reference to 'locker-room talk'".
While the National Football League refuses to comment on whether Trump's non-stop attacks on the anthem protesters contributed to the rule change, some players think it did. Teams have the option of levying fines against individual players if they demonstrate.
The league announced last week that players who kneel during the anthem on the field would be fined, but they can stay in the locker room if they want to protest.
But Jones was reluctant to give Trump too much credit for influencing the league... But some fans grew exhausted of the displays, and President Trump hammered protesting players.
"This is a very winning, strong issue for me", the President told Jones, according to Andrew Beaton of the Wall Street Journal.
While the quote from Jerry Jones' telephone conversation with Trump is news, the fact that the president was a force in the NFL's decision to alter its anthem policy, is not news. A White House official did not dispute the testimony.