Penny pleaded not guilty to second-degree manslaughter and criminally negligent homicide.
Witnesses say the man, Jordan Neely, had been shouting and demanding money when Penny approached him on May 1, 2023.
Thats when Penny moved to restrain him, pinned the man to the floor of an NYC train with the help of two other passengers, and placed him in a chokehold until his body went limp.
The medical examiner's office ruled his death a homicide. Penny's lawyers argue that the Long Island native didn't intend to kill Neely but rather sought to hold him down long enough for police to arrive.
The case has fueled political narratives and perceptions about urban crime and captivated a city in which the subway is indispensable.
The judge has said it could take two weeks to seat a jury that will be asked to reconcile with when it is appropriate for a citizen to kill another citizen.
Neely was apparently experiencing homelessness and was known to perform as a Michael Jackson impersonator. Penny's defense has argued Neely was "insanely threatening" to passengers aboard the F train in Manhattan and Penny "took action to protect the lives of others."
Prosecutors in the Manhattan district attorney's office are expected to concede that Neely may have seemed scary to some subway riders but will argue Penny continued the chokehold long past the point where Neely stops moving and poses any kind of threat.
To convict, prosecutors must prove Penny's use of lethal force was unjustifiable and that Penny acted recklessly and consciously disregarded the substantial risk of putting Neely in the chokehold for so long. Prosecutors do not have to prove Penny intended to kill Neely, which defense attorneys have said he did not.
"We are confident that a jury, aware of Danny's actions in putting aside his own safety to protect the lives of his fellow riders, will deliver a just verdict," Penny's lawyers, Steven Raiser and Thomas Kenniff, have said.
The case is expected to feature testimony of passengers who were aboard the subway at the time and video of the chokehold, which lasted six minutes. Prosecutors have said that about 3 minutes and 10 seconds into the video, Neely is seen ceasing all purposeful movement.
"After that moment, Mr. Neely's movements are best described as 'twitching and the kind of agonal movement that you see around death,'" prosecutors have said.