The manslaughter trial of former Marine Daniel Penny for choking a homeless man who was scaring subway riders reflects the considerable divisions in our world today. To some, Penny is an urban hero — a good Samaritan — who risked his own safety to protect vulnerable subway riders. To others he is just a racist white man who is guilty of yet “another lynching of a Black man.” These extreme views hide the complexities not only of this particular case but of the law regarding the right of citizens to use force to protect other citizens. The basic external facts are not in dispute: Neely was screaming and frightening subway riders including women and children. Penny grabbed him around the neck and held him for approximately 6 minutes. He died as a direct result of the chokehold. Cell phone videos confirm these basic facts. What is in dispute is whether Penny intended to kill Neely — he categorically denies such an intent. And even if he did not intend to kill, whether his conduct was so reckless under the circumstances that he should have known that death was a likely result. There is also a dispute over whether Penny reasonably believed that Neely posed a danger of physical harm to passengers, beyond just disturbing them. A jury of 12 New Yorkers will decide the contested issues. Most critically, the judge will have to decide whether to admit evidence of Neely’s long and sordid history of violence prior to his subway encounter with Penny. Since Penny was not aware of this long trail of violence, it could not have affected his state of mind. So the jury will probably not know that Neely had been arrested more than 40 times, including most recently for punching a 67-year-old woman in a subway station. Nor will they learn that there was a warrant out for his arrest on the day of the crime. Had Penny known about this history, he would’ve been entitled to take that into account in assessing Neely’s dangerousness. But judges tend to exclude such evidence unless the defense can show its relevance to the defendant’s state of mind. Jurors will hear that Neely was throwing garbage and that Neely was shouting that he was tired of being hungry and was “ready to die” or “go to jail.” They will also learn that two other passengers held Penny, including one who is also Black. But they will probably not learn of his violent history, including his recent attack on the elderly woman. The rules are different when it comes to evidence of the defendant’s prior history. The jury will almost certainly hear evidence of Penny’s good character, his service in the Marines, his lack of any history of racism and other factors that might incline jurors to be sympathetic. Much will also turn on the instructions the judge gives to the jury. If they must conclude beyond a reasonable doubt that Penny intended to kill Neely, they will have to acquit. But the judge may allow jurors to convict on the basis of some degree of negligence in maintaining a chokehold for so long a period of time. The jury will then have to assess the continuing danger Penny believed Neely posed as he continued to hold him. This is reminiscent, at least to some degree, of the George Floyd case. Among the differences, however, is that the defendant in the Floyd case was a police officer. Here the defendant is an ordinary citizen, albeit a former Marine. On the one hand, a police officer has a greater duty to intervene than does an ordinary citizen; on the other hand, a police officer is supposed to be better trained on the dangers of a chokehold. Depending on the evidence that will be admitted at the trial, this could be an extremely close case. Much may also depend on jury selection. Considering the divided views in New York regarding race and violence, the result may well be a hung jury. This raises the policy issue of whether this manslaughter case should have been brought at all. Public pressure from progressives has demanded accountability. But district attorneys should not be influenced by such pressures. Criminal cases should be clear and not subject to reasonable interpretations of innocence. In our view, this case is too close — on the facts and law — to have become the basis for a criminal prosecution. Dershowitz’s latest book is “War on Woke: Why the New McCarthyism Is More Dangerous Than the Old.” Stein is a former president of the New York City Council.