Judging the immorality of the four police officers charged with the death of George Floyd is easy. Floyd was handcuffed and on the ground, with four armed officers over him. All the police had to do was listen and stop—he would still be handcuffed, he would still be unable to harm them; but he could be permitted to breathe anew. Ignoring that, or not intervening or at least protesting a fellow officer's behavior, is indisputably inhumane.

But the criminal law and morality lack a perfect overlap. What warrant examination are the charges that have been brought and whether and how they can justly apportion legal blame.

Minnesota Attorney General Keith Ellison, after announcing charges against the four officers, cautioned that "winning a conviction will be hard … because history shows that trying and winning a case like this one is hard." Ellison was referring to the historic reluctance of jurors to convict police acting in the line of duty in what are often fraught circumstances, especially where the deceased is a racial minority. But "winning a conviction" is also dependent upon the criminal law as written and how jurors might apply the terms of each statute to each of the four defendants.

If it were a question of morality alone, the charge of first degree murder would seem warranted, for what is worse than people entrusted with power misusing it flagrantly and with ample time to rethink and retreat. Yet that is not how this crime is defined. Minnesota has two intentional murder crimes, one with and one without premeditation. Callous disregard for life, mean-spiritedness or whatever malicious thought was going through the mind of Derek Chauvin for more than eight minutes, trying to prove his goal was the death of George Floyd may be impossible.

The main charge brought against the four is second degree [felony] murder. Unlike Pennsylvania, which limits the underlying felonies that may trigger this charge, Minnesota allows the charge where death is unintended but results "while committing or attempting to commit a felony offense … with force or violence …" A felony assault occurs when there is bodily injury that causes a temporary but substantial loss or impairment of the function of any bodily member or organ." Cutting off breathing seems to fit that charge, at least as to the lead defendant, Derek Chauvin. Where it gets complicated is with the three remaining defendants.

Two others used their body weight to hold Floyd to the ground. The private autopsy commissioned by the Floyd family laid blame on all three—together they asphyxiated George Flood, causing his death. The county medical examiner's report is less clear. If the two can be shown to be proximate causes of the death, then each must still be judged as to whether he committed an assault. If "yes,' felony murder; if "no," maybe still as accomplices, a concept discussed below.

What about lesser charges? Chauvin was originally charged with third degree murder, one carrying a lesser punishment—a maximum of 25 years as opposed to the 40 years in second degree murder cases—but possibly harder to prove. That crime requires "perpetrating an act eminently dangerous to others and evincing a depraved mind, without regard for human life," terms that have no easy definition and may vary in the eyes and conscience of each juror. The final charge is manslaughter, a negligent act in which "the person creates an unreasonable risk, and consciously takes chances of causing death or great bodily harm to another." The fight on this charge will be whether there is a believable explanation from any of the defendants that "I didn't realize … "

Whether murder or manslaughter, the autopsy findings point directly at the lead defendant in terms of causation. But what of the two who were pinning George Floyd down, and the officer who stood by? Will they escape blame if they are not found to have caused the death?

A jury will have to assess each defendant's thought process, for to be culpable as an accomplice the prosecution must prove that the defendant knew Chauvin was going to commit a crime and intended his presence or actions to further the commission of that crime. What morality may say should not count is what the law may require to be weighed—whether all clearly heard the cries of "I can't breathe;" what significance should be given to Chauvin being the training officer for two of the others; and a second-by-second assessment of the conduct of the fourth officer who stood by [or over] the others.

These are legal issues the jury will have to confront, and that assessment may be made more complex by a trial that likely will include attempts to blame Floyd, finger-pointing among the defendants, and arguments on police decision-making in the moment.

All of this will lead to a narrow set of decisions—which laws, with their requisite mental states, have been proved beyond a reasonable doubt to have been broken. While criminal laws reflect moral choices of the Legislature, the jurors will be forced to act within the confines of those statutes and do their best to determine legal blameworthiness. That is a much narrower judgment than the moral judgment that is due on both the four defendants and the system that led to Floyd's death.

Jules Epstein is professor of law and director of advocacy programs at Temple University Beasley School of Law.