FILE - Protestors gather outside of the courthouse on the first day of jury selection for Baltimore Police Officer William Porter who is  charged in connection with the death of Freddie Gray, in Baltimore, Md., Nov. 30, 2015.
FILE - Protestors gather outside of the courthouse on the first day of jury selection for Baltimore Police Officer William Porter who is charged in connection with the death of Freddie Gray, in Baltimore, Md., Nov. 30, 2015.

BALTIMORE - He didn't fire a gun or wield a Taser. He didn't place anyone in a chokehold or wrestle anyone to the ground. In fact, William Porter barely touched Freddie Gray.

But Porter, the first officer on trial in Gray's death, is accused of manslaughter for failing to pay enough attention to the 25-year-old black man, who was handcuffed and shackled in the back of a police van and suffered what would be a fatal spinal injury.

Proving a negative: In Porter case, inaction is on trial

His crime, according to prosecutors, is failing to immediately call a medic to the scene when Gray indicated he needed medical attention and ignoring a Baltimore Police Department general order requiring officers to buckle prisoners in with seat belts.

FILE - William Porter, right, one of six Baltimore
FILE - William Porter, right, one of six Baltimore city police officers charged in connection to the death of Freddie Gray, walks into a courthouse with his attorney Joseph Murtha for jury selection in his trial, Nov. 30, 2015, in Baltimore.

Jurors will begin deliberating on Monday. But with no eye witnesses and no unequivocal evidence as to exactly how or when Gray was injured, negligence could be difficult to prove, legal experts say.

"Usually, criminal law has to do with intentionally doing something -- stealing, assaulting," said Baltimore attorney David Irwin, who recently represented an Episcopal Church bishop in Maryland. The bishop pleaded guilty to vehicular manslaughter and other charges because she left the scene of a crash with a cyclist and failed to call an ambulance.

Present on van ride

Porter was present during five of the six stops the police van made during the 45-minute ride between Gilmor Homes, where Gray was arrested when he ran from officers, and the Western District station house, where Gray arrived unresponsive. He died a week later.

Porter, who testified on his own behalf, told jurors that Gray wasn't visibly hurt and didn't exhibit any signs of distress when the officer offered him aid. Porter testified that Gray never once asked for a medic, but simply said "yes" when Porter asked if he'd like to go to the hospital.

Porter said he told van driver Caesar Goodson to take him there, because while he still didn't believe Gray was really hurt he knew the jail would reject a prisoner claiming injury. He didn't think it was an emergency, he told investigators, because Gray had been kicking inside the van at a previous stop, and "he didn't appear hurt in any way, shape or form."

Baltimore police officers charged in Freddie Gray'
Baltimore police officers charged in Freddie Gray's death, top row from left, Caesar Goodson Jr., Garrett Miller and Edward Nero, and bottom row from left, William Porter, Brian Rice and Alicia White.

Porter testified along with other defense witnesses that included a law enforcement expert and a Virginia police chief that it would have been van driver Caesar Goodson's responsibility to buckle Gray into a seat belt, though officers are permitted to skip the seat belt if they feel they're in danger or at risk.

Instead of going to the hospital, Goodson picked up a second prisoner and drove both men to the station. By the time they arrived, it was too late.

Steve Levin, a Baltimore-based attorney and former federal prosecutor who has represented Baltimore police officers in the past, said the charges are unusual based on what he knows about the case.

"It'd be difficult to prove that Mr. Porter's failure to follow policy caused Mr. Gray's injuries," he said. "It's easier to prove affirmative misconduct than misconduct by failing to do anything at all."

Unusual case

That's because of the way American laws are written, according to David Harris, a law professor at the University of Pittsburgh who specializes in policing, adding that the Porter case is unusual "not just in police cases but in criminal law."

"The criminal law is set up as 'thou shalt not kill, steal, rob, break.' We handle criminal conduct in terms of things that people are prohibited from doing. 'You may not,' " Harris said. "It's fine to tell us what not to do, but we don't like to be told you must. That current runs very deep in the American psyche. When it comes to criminal liability for criminal omissions we're very stingy about how we allow that."

Gray's death from a critical spinal injury is not the first in Baltimore's recent history: an eerily similar case 10 years earlier saw civil litigation but no criminal charges.

Similar case

In the case of Dondi Johnson, a man who died in 2005 two weeks after suffering a near-identical injury as Gray in the back of a Baltimore police wagon, his family won a $7.4 million judgment after suing the police. The officers who transported Johnson were never criminally charged, and in fact, two of the three remain on the force despite the lawsuit's finding of liability due to negligence.

Gray's family settled with the city for $6.4 million without ever filing a lawsuit.

Tonya Kelly, a defense attorney and former state prosecutor, said there are implicit realities that come with being a police officer that jurors will likely consider: Porter's duty to act, and his understanding of certain policies that require him to do so. Still, she said the state's case is a difficult one to prove.

"If you don't know when the injury occurred, how can you possibly tie his inaction to Freddie Gray's harm? There are so many facts that aren't linear," Kelly said.