Floyd Abrams, a constitutional law expert who has appeared frequently before the Supreme Court, said  Sunday that CNN has a case.
“I think it’s a really strong lawsuit,” Abrams said. “I can understand CNN being reluctant to sue because the president keeps saying CNN is the enemy of me, and CNN might have reluctance to have a lawsuit titled ‘CNN vs. Donald Trump.’ That said, yes, I think they should sue.” Abrams said.
Last Wednesday, The White House suspended the CNN chief White House correspondent hours after Acosta pressed Trump at a press conference. Acosta was forced to turn in his Secret Service “hard pass.” which speeds up entry and exit from the White House.

Source: First Amendment lawyer says CNN should sue the White House over Acosta ban – CNN