Is the ban justified? Can CNN sue? Questions about the White House's action against Jim Acosta answered

(CNN) The Trump administration has blocked CNN chief White House correspondent Jim Acosta from accessing the White House. This is an extremely unusual step for an American government to take, and it has been met with widespread criticism and calls for the White House to restore Acosta's press pass. Here's the latest:

Is Acosta still banned?

Yes. He found out his Secret Service "hard pass," which speeds up entry and exit from the White House, was being suspended on Wednesday night. More than 24 hours later, he is still banned from the White House grounds.

CNN is working behind the scenes on a resolution that would restore Acosta's pass.

Why is this happening?

CNN says the revocation of his pass on Wednesday night "was done in retaliation for his challenging questions at today's press conference."

Press secretary Sarah Sanders explained it differently. She said Acosta's conduct at Wednesday's post-election press conference was "absolutely unacceptable." She cited Acosta's refusal to immediately hand over a microphone to a White House intern while he was asking questions of the president. Sanders said the administration will "never tolerate a reporter placing his hands on a young woman just trying to do her job as a White House intern."

But video of the event shows that Acosta did not mistreat the intern. "Pardon me, ma'am," he said, when she reached for the mic. After asking another question, he gave her the mic.

CNN said in a statement that Sanders "lied" about what happened. "She provided fraudulent accusations and cited an incident that never happened," the network said.

What led up to this?

Acosta has been a thorn in the side of the administration ever since Trump was inaugurated. He has been one of the most aggressive reporters on the Trump beat, winning him huge numbers of fans as well as critics. While some media critics say he's a showboat, he says his style is effective -- and necessary -- at this moment in time. Some Trump-supporting commentators called for his credentials to be revoked in the hours before the White House took action on Wednesday.

What is Acosta saying?

On Thursday morning, he tweeted, "Don't believe the lies coming from the WH. Believe in our freedoms. Thank you all for your support. We won't back down."

So what is Acosta doing now?

He's still reporting. On Thursday evening he reported that that Labor Secretary Alex Acosta (no relation) is under consideration for the open Attorney General job, citing two sources.

Acosta is on the way to Paris to cover President Trump's trip to France, CNN said Thursday night.

What are press advocates saying?

More than a half dozen prominent advocacy groups, from the Committee to Protect Journalists to the ACLU, have condemned the White House's action and demanded that his hard pass be reinstated. The White House News Photographers Association issued a statement expressing outrage that Sanders "may have shared a manipulated video."

What is a "hard pass?"

It is a security credential that reporters who regularly cover the White House use to expedite their entry and exit. Historically the passes have not been used to punish reporters.

Has anything like this happened before?

White House historians and professors were hard-pressed to think of any exact parallel to this case. CNN's statement called it "unprecedented." The closest comparison might be the case of Stuart Loory, who was ejected from the Nixon White House after writing stories that challenged the then-president.

What about CNN's other reporters?

The suspension only applies to Acosta. All of CNN's other reporters, producers and photojournalists continue to work from the White House grounds.

Are any reporters boycotting the White House as a result?

Not that we've seen, but journalists from across the media landscape have publicly lambasted the White House for its accusations against Acosta. One complicating factor: The lack of a daily press briefing. The Trump administration has phased out the daily on-camera briefings and opted to hold them on a sporadic, unpredictable basis. This removes one setting where in which reporters could show solidarity with Acosta.

Could Acosta or CNN sue?

Some experts say yes. "Acosta and CNN have legal grounds to challenge the White House's decision," Jonathan Peters, a media law professor at the University of Georgia, told CNN. "Relevant precedent says that a journalist has a First Amendment right of access to places closed to the public but open generally to the press. That includes press rooms and news conferences. In those places, if access is generally inclusive of the press, then access can't be denied arbitrarily or absent compelling reasons. And the reasons that the White House gave were wholly unconvincing and uncompelling."