On Monday, a jury will begin deciding the fate of William Porter, the first of six Baltimore Police Officers charged in the death of Freddie Gray.
Prosecutors argue that Gray, a 25-year-old who was arrested for the relatively minor offense of possessing an illegal switchblade, died last April because the officers administered a 45-minute "rough ride" when transporting him. What happened inside that van is pivotal -- and it separates this case from many recent controversial police shootings around the nation. Those cases typically turn on whether a free suspect posed a serious danger, which can be a close call in the field.
By contrast, Gray was already in custody, injured, and outnumbered six-to-one when he sustained deadly spinal injuries.
The most serious charge facing Porter is involuntary manslaughter – the kind of accidental killing usually associated with a car accident.
Prosecutors are focusing on Porter's failure to take basic measures to protect Gray, such as failing to get him medical care or seatbelt him. Porter's defense argues he didn't know Gray was injured for most of the ride, and he didn't usually seatbelt arrestees in the van.
Both sides will hit those themes again in closing arguments Monday, before the case is handed to the jury. As the first of six trials, experts say the outcome of Porter's case could loom large.
Robert Bonsib, a former Maryland prosecutor, says when prosecutors have a series of trials about the same incident, they usually begin with the strongest case.
“In most criminal cases you take your best case first -- the individual who is most culpable -- but in this case, Porter’s statements are more valuable, so he went first," Bonsib told MSNBC.
Prosecutors say Porter made initial statements that hurt his defense. Other officers face more serious charges, such as Caesar Goodson, who will go on trial next, for second degree murder, in January.
Former Maryland prosecutor Andrew Radding thinks the Porter trial will set the tone for the remaining cases.
“If he’s acquitted, it will take the wind out of the other cases and will be a blow to the state,” Radding told MSNBC.
Ty Williams, another former Maryland prosecutor, notes that while juries must assess each officer's mentality and culpability, the first verdict can feel like a template for the rest.
“State of mind differs in each case, but factually this first trial will set the stage,” said Williams, who now practices criminal defense.
As a technical legal matter, she added, each trial "stands independent." There is a separate set of jurors, for example, finding facts in each officer's case. But prosecutors and defense attorneys know that mood and momentum also matters.
While the Baltimore cases have drawn national attention since protests erupted after Gray's death, as a matter of precedent, it would actually be extraordinary if any of the officers were convicted in Gray's death.
The fact remains that U.S. police are almost never charged for on-duty shootings, and in the few times they are, convictions are rare.
But according to research by criminal justice professor Philip Stinson, over the past decade, only about 5 officers are charged annually for deadly shootings. That number ticked up to 15 this year, with 10 of those indictments based on video evidence.
If any of the Baltimore officers are convicted of charges related to Gray's death, it would be a rare event not only for Baltimore, but the entire country.
"If any of the officers are convicted for Freddie Gray's homicide, it will likely be the first time for a Baltimore police officer in the line of duty," says Debbie Hines, who tried homicide cases as prosecutor in Baltimore. "The case could speak volumes," she told MSNBC, "for public and legal ramifications.”