BALTIMORE (WJZ) — On hold. An indefinite delay for the trial of Officer Caesar Goodson. He faces the most serious charges of the six city police officers charged in the death of Freddie Gray.

WJZ Investigator Mike Hellgren breaks down what’s behind the delay and what happens next.

State’s Attorney Marilyn Mosby looked confident as she entered the courthouse, despite a last minute order from Maryland’s second highest court, postponing the trial of Officer Caesar Goodson Junior and putting her prosecution into limbo.

“There’s a lot at stake here for all of the criminal defendants in Maryland,” said Doug Colbert, University of Maryland law professor.

The hitch is the prosecution’s star witness — Officer William Porter — a man they’ve previously called a liar.

Porter’s lawyers argue he should not have to testify because he faces his own retrial and possible federal prosecution, and the limited immunity he’s being offered is not enough to protect him.

“The state argues that he’s just a witness, but the reality of it is, of course, is that he’s also a defendant,” said Warren Alperstein, lawyer and courtroom observer.

Another big question that could delay the case even more is if it will be appealed beyond this to the state’s highest court.

“It could take weeks, it could take months. You just never know what the Court of Special Appeals will do,” said Alperstein. “This could ultimately be a landmark decision.”

Protesters worry the postponement means there won’t be justice for Freddie Gray in Baltimore.

“I think it’s criminal. I think it’s a damn shame,” said one man.

Officer Porter’s testimony against Officer Goodson is so crucial for prosecutors, they argue their case would be irreparably harmed without it.

Porter has claimed he notified Officer Goodson, who was driving the van, that Freddie Gray needed medical attention.

Goodson is the only officer to face a murder charge.

“Every day something different happens, which I think makes it even more unusual, quite frankly,” said Alperstein.

It all leaves an uncertain road ahead now for all of these high-profile, high stakes trials.

Goodson’s lawyers were pushing for the trial to start Monday with the prosecution in such a state of limbo.

The Court of Special Appeals has up to three months to make up its mind. We do expect it to take less time than that.