Ferguson protesters insisted at a raucous meeting on Saturday that Gov. Jay Nixon act quickly to charge Ferguson officer Darren Wilson with murder in the shooting death of Michael Brown.

St. Louis on the Air discussed this and other legal issues associated with Ferguson on Monday:

As straightforward as that sounds, Nixon can’t do it. The governor does not have the power to charge a person – any person – with a crime. “All” power to charge a person with a crime resides under state law with the prosecuting attorney, in this case St. Louis County Prosecuting Attorney Robert McCulloch.

In the context of the Brown shooting, this may seem unfair to protesters. But there is reason behind it: People wouldn’t want the governor to have the power to put people in jail.

“The prosecutor of any jurisdiction has sole discretion to bring charges against a potential defendant,” said Marcia McCormick, a professor at Saint Louis University Law School. “Nothing can make that prosecutor bring charges when he or she does not want to.”

The governor’s lack of power to initiate a prosecution is one example of how the law may require a different course from the one that seems most fair to protesters. Here is a legal primer answering some of the complicated legal questions:

Why wasn't the officer arrested at the scene and charged with murder?

Police officers have the authority to use deadly force when it is reasonable and necessary and usually are not second-guessed. Experts could not think of a case when an officer accused of misusing deadly force was arrested at the scene.

“Police are not usually indicted for this,” said David Harris, an expert on policing at Pitt Law School. “In the majority (perhaps great majority of cases), shootings by officers are found to be justified. Officers do have the power to use force, even deadly force, when reasonable and necessary in the performance of their duties, so they get the legal benefit of the doubt.”

If there is a criminal indictment, would it be for murder?

Not first-degree murder. Second-degree murder is possible, but voluntary manslaughter may be more likely.

McCormick said, “Depending on what the evidence shows, it could be second-degree murder — knowingly causing death. A prosecutor could decide that the definition of voluntary manslaughter is more appropriate — knowingly causing death under a sudden passion with adequate cause (an assault on the officer).”

Could Nixon or St. Louis County Executive Charlie Dooley remove McCulloch, who has been accused of favoring the police partly because his father was a St. Louis officer killed in the line of duty?

No. Michael Wolff, dean of Saint Louis University Law School, put it this way: “Dooley can call for a special prosecutor all he wants, but there is no legal cause for one unless McCulloch recuses himself and his office.”

Nixon could order Attorney General Chris Koster to provide the prosecutor with “aid,” in any criminal investigation, but McCormick wrote in an email, “It's not clear that the governor has the power to do this without a request by the prosecuting attorney.”

The death of McCulloch’s father does not pose a legal conflict of interest or require him to step aside, lawyers agree.

Would the video of Brown’s alleged robbery of a convenience store a few minutes before the shooting be presented to the grand jury?

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Yes. McCulloch already has said publicly that he planned to show the store video to the grand jury, and there are no rules of evidence in a grand jury.

“The grand jury is really a tool of the prosecution, although it can provide some sort of check,” said McCormick. “Only the prosecutor may appear, present evidence, examine witnesses and give the grand jury advice on what the law means. There are no rules governing the evidence that the grand jury may be presented or may ask for — so of course the video can be shown to it. It is extremely rare for a grand jury not to return an indictment that the prosecutor wants issued since the prosecutor controls all of the information given.”

She added: “In this case, it might be politically savvy for the St. Louis prosecuting attorney to present an extremely weak case to the grand jury, full of good information about the officer, bad information about the victim, and no information that would suggest the shooting was not justified. That would provide political cover.”

Would the video be admitted into evidence at a trial if Wilson were charged?

Most likely. Just because McCulloch presents the video to the grand jury does not mean he would necessarily present it at trial. It would weaken his case for conviction. He could even end up objecting if the defense tried to offer the video into evidence, said Roger Goldman, an emeritus professor at Saint Louis University Law School. But he added, it’s “my guess that judges in criminal cases would bend over backward not to exclude.” Arguably, the video is relevant to Brown's state of mind and possibly Wilson's as well. (Editor's note: The previous sentence originally did not include that the video might be relevant to Brown's state of mind. It was changed in response to further information from legal experts.)

Would a St. Louis County jury be likely to convict?

No. “Asking a jury to convict a cop is really hard in most jurisdictions,” wrote Pitt’s Harris in an email. “To most jurors, cops are the good guys, and the people shot are often (not always) bad guys or not clean.”

In addition, while Ferguson is two-thirds African American, the jury that would hear the case would come from St. Louis County as a whole, Goldman notes. The county is 70 percent white.

Why are there two investigations — a federal and state one?

The state investigation is for violations of state law — such as murder or manslaughter.

The federal investigation conducted by the Justice Department is for violation of Brown’s federal rights. The federal law passed after the Civil War, makes it a crime to deprive a person of “any rights, privileges, or immunities secured or protected by the Constitution or laws of the United States.” When death results, life in prison or even the death penalty are punishments.

Why aren’t two prosecutions double jeopardy?

The Supreme Court has said that different sovereigns are involved — federal and state.

Which prosecution goes first?

The state prosecution goes first, although the FBI often conducts its investigation at the same time as the state. That is what it is doing in the Wilson/Brown case.

Does the federal government always prosecute when a state prosecution fails?

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No. Dual prosecutions are relatively rare. An example of one that was successful was the prosecution of Los Angeles police in the Rodney King beating after the officers had been cleared on state charges. The state verdict had prompted deadly riots in Los Angeles.

Does the federal government usually win its civil rights prosecutions?

No. The federal prosecution requires a high level of proof because it requires proof that the officer specifically intended to deprive the victim of his civil rights. That “makes it very hard to convict,” wrote Pitt’s Harris. “DOJ takes a very small percentage of police violence cases they get to indictment phase.”

Goldman pointed out that “it doesn't matter whether there is an actual threat when force is used. Instead, what matters is the officer's ‘objectively reasonable’ belief that there is a threat.” In other words, Wilson’s lawyers could argue that he had an objectively reasonable belief of a threat after the struggle he's alleged to have had with Brown over the gun — even if there was not an actual threat.

In addition, federal juries in this area are taken from a pool that is about 90 percent white, Goldman said.

Can police shoot a fleeing felon who is unarmed?

Generally no, but the fleeing felon must not pose a danger. The typical case of a fleeing felon involves a teen fleeing a burglary without a gun. The U.S. Supreme Court ruled that shooting in this kind of case is unconstitutional.

But the Wilson/Brown case is different because Brown would have been considered dangerous if he was struggling with the officer for the gun.

The Ferguson case might present an unusual set of facts. Police accounts so far say the situation involved a dangerous suspect fighting an officer, then taking off unarmed. Would Brown then transform from a dangerous to a non-dangerous fleeing suspect? Some witness accounts suggest that Brown turned around and came back toward Wilson. That could bolster the claim that he was a dangerous suspect.

These questions and more will be discussed on St. Louis On the Air on Monday at noon.