Ari Melber is MSNBC’s chief legal correspondent.
Cuyahoga County Prosecutor Timothy McGinty announced that a grand jury will not bring charges against police officers involved in the killing of 12-year-old Tamir Rice, who was carrying a toy gun. (Reuters)

There’s a legitimate debate about whether the Cleveland police officer who killed Tamir Rice, a 12-year-old boy holding a toy pellet gun, should be charged with any crime.

There is really no legal debate, however, that the Ohio prosecutor handling the case, Tim McGinty, turned the grand jury process upside down.

McGinty, who led a year-long inquiry into the shooting, announced Monday that a Cuyahoga County grand jury voted against charging the officers and was candid about helping lead them there: “The Grand Jury declined to bring criminal charges,” he said. “That was also my recommendation, after reviewing the facts and the law.”

Grand juries are built to be a tool of prosecutors. They don’t hear from both sides in a case, like a trial jury would. They hear only from the prosecutor, who decides what evidence and testimony is presented.

That’s why the old saying goes that a grand jury will “indict a ham sandwich” if a prosecutor tells them to — because the prosecutor calls the shots. That saying, however, assumes the prosecutor wants to prosecute and, ultimately, secure a conviction.

The Rice case strongly suggests that the opposite is also true — grand juries will let the sandwich walk, if that’s what the prosecutor wants. In this case, McGinty used the grand jury as more of a sounding board for an exoneration of the potential defendants, rather than as a review of possible charges against them.

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His 70-page report reads like defense counsel brief, not a neutral assessment of potential charges. (It even has headings like “Officers Loehmann and Garmback’s subsequent statements are consistent with the evidence in this case” and “The incident conforms to the Cleveland Police Department’s active shooter policy.”)

This approach — using the grand jury to review arguments on behalf of potential police defendants, not to prosecute them — fits the model of several recent inquiries of police shootings.

Just last week, Texas prosecutors announced that a grand jury declined to charge any Waller County jail officials in the death of Sandra Bland, a 28-year-old woman who was arrested after a routine traffic stop caught on video and was later found dead in her cell. Jail staff said they discovered her hanging by a plastic bag, an apparent suicide. Her family maintains that the circumstances are suspicious.

Prosecutors convened the grand jury to consider potential charges against the jail staff but then said they already concluded that her death was a suicide.

Which makes no sense.

If Bland killed herself, there is no crime to charge. The grand jury should have no charges to bring, and nothing to review.

If prosecutors believed she was killed, then they should have presented those charges to the grand jury. But the Texas prosecutors gave away their game by saying, essentially, that they asked jurors to consider potential charges for a crime they say didn’t happen. If that sounds hard to follow, it is, because the prosecutors are obfuscating on purpose.

Prosecutors in these cases hide behind the grand jury process, one that is supposedly independent, while pushing grand jurors toward their decision, all the while claiming that juries might have reached different conclusions.

As a legal process, it’s reminiscent of those maddening staircase sketches by M.C. Escher, with each flight of stairs collapsing into another flight of stairs, an endless optical illusion. You can’t follow the logic because there is none.

If that feels like too sweeping a critique, consider more of McGinty’s own words on Monday: “Justice would not be achieved by bringing charges that would violate the ethical canons of our profession because we know these charges could not be sustained.”

In other words, McGinty not only decided against charges — a judgment call — but felt that such charges are so egregiously wrong that filing them against the officers would violate his ethical duties.

Which is certainly his call to make. The professional association for lawyers, the American Bar Association, states that prosecutors have a special responsibility not to bring charges they know aren’t “supported by probable cause.”

Yet McGinty’s stated concern brings the entire dilemma back to the same point.

The grand jury has only two possible outcomes: charges or no charges. If one of them is literally an ethics violation, then he should not be presenting that option to the grand jury in the first place.

It’s a trap that is inevitable anytime a prosecutor asks a grand jury to consider charges the prosecutor strongly opposes.

The trap arose for the Bland grand jury in Texas, where the available evidence didn’t establish whether the death was a suicide or homicide. The trap was present in the Michael Brown shooting in Ferguson, Mo., where the grand jury heard mixed messages from a prosecutor who had decided that the officer acted lawfully. And it was on display yesterday in Ohio, where video evidence established the killing of a child, leaving only a legal question about whether that killing was justified.

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The facts of those cases differ greatly, but each time, prosecutors invoked the grand jury process to sign off on — and, in effect, clear — their own decision not to charge officers. Prosecutors defend this practice, it’s worth noting, as a way to double-check their work, provide information to the public and give citizens a voice. McGinty even says he decided to use a grand jury for all police shootings, as an office policy.

These cases have exposed the failures of this model, however, for both citizens and officers alike. In instances of clearly justified police shootings, there’s no good reason that officers should face an automatic grand jury review of potential charges. As Americans, we ask police to risk their lives and sometimes take the lives of others — there’s no policy rationale for making their jobs more litigious simply because a prosecutor wants a uniform rule or political cover. We don’t need a grand jury, for example, to review the effective work of the officers who killed the San Bernardino shooters.

At the same time, prosecutors have an obligation to vigorously pursue potential crimes, no matter who commits them. It breeds mistrust and cynicism if the public believes prosecutors apply a different process and set of standards depending on the identity of a suspect.

Our founders put grand juries in the Constitution so that citizens could check overzealous prosecutors. As the Supreme Court noted in 1992, the purpose of a grand jury is to confirm that there is some “basis for bringing a criminal charge.”

In that 8-to-1 decision, the court explained, “It has always been thought sufficient to hear only the prosecutor’s side” before jurors give a green light for a prosecutor’s proposed charges. It is a historical oddity that today some prosecutors are using grand juries to present the defense’s side and avoid any charges at all.

Correction: This story initially said officials reported Sandra Bland’s death as a suicide involving a belt. In fact, officials reported that her death involved a plastic bag.