Kilkenny-born Doctor Martin Tobin, 69, an Irish physician who simply says his expertise is “breathing”, has come to dominate the Derek Chauvin trial which Newsweek called “among the most consequential events of the 21st century." MSNBC simply called it “The Trial of the Century.”

So effective was his testimony that African American leaders are calling for it to be included in all police training videos nationwide.

Tobin is a renowned expert in his field. The American Thoracic Society called Tobin  "the supreme scholar of critical care medicine and editor or author of seven extraordinary textbooks on the subject." He is a former editor of the American Journal of Respiratory and Critical Care Medicine.

Thousands of Americans on social media and cable news agree the testimony was powerful.

Wow Dr. Tobin didn’t come to play: he created a birds eye view graphic that combined all the different points of view provided from bystander camera footage and shows us this: #ChauvinTrial

— dailyL (@dailylaney) April 8, 2021

MSNBC Host Joy Reid said that “Doctor Tobin has changed it (medical trial testimony) forever.”

Dr. Martin Tobin ... Will be remembered for generations to come. #GeorgeFloyd #ChauvinTrial

— Kimathi Githachuri (@Githachuri) April 8, 2021

Above are just three of the incredible tributes paid to Tobin who turned into the key trial witness by simply arguing the true reasons for the death of George Floyd.

He found that Minneapolis police officer Derek Chauvin keeping his knee on Floyd’s neck for over 9 minutes was the central reason for the death and Floyd’s demise was not in any way drug-related, which has been the defense’s main argument.

Floyd’s death led to the explosion of protest across the United States last summer and the empowerment of a worldwide political movement called Black Lives Matter.

Yet always unspoken was whether the generations-old bias in favor of police officers who kill black men would prevail despite the awful crime and somehow allow Chauvin to get away with it.

That still seemed possible at the beginning of the trial when it was revealed that Floyd had narcotics in his system and the coroner ruled that may well have been a major factor in his death.

Then came the extraordinary testimony of Freshford, County Kilkenny’s new favorite son.

Tobin’s family ran a bakery shop in the small town but the family could hardly have realized how high their son would rise in the medical world.

He is now a world expert on pulmonology but explained himself so simply that he caught on with the massive worldwide audience watching the trial right away as well as the jurors, say media members who were in court.

Though he has written numerous books and done groundbreaking research on pulmonology, Tobin simply referred to himself as ’’an expert on breathing” at the beginning of his testimony.

His low-key simple descriptive style eschewed all complex medical terms.

Floyd died because of “low oxygen” he explained simply which had nothing to do with the drugs he had in his system. Any person drugged or not would have died the way he was being crushed by the three police officers.

Here is how clear he was. “Mr. Floyd died from a low level of oxygen, The cause of the low level of oxygen was shallow breathing, shallow breaths that weren’t able to carry the air through his lungs down to the essential area of the lungs that get oxygen to the lungs and get rid of the carbon dioxide.”

Tobin, who studied at University College Dublin and Trinity College practiced for a time in Miami, Texas, and Pittsburg. He now practices in Illinois at Loyola University Medical Center. He explained that half of Chauvin's weight - about 83 pounds - was kneeling on Floyd’s neck. The other policemen blocked any hope of allowing him to breathe by crushing him against the gravel and holding him down in a prone position, handcuffed.

In sum total, Floyd who had been arrested for trying to pass a fake $20 bill went through living hell as the life was slowly crushed out of him, Tobin said. What happened was the equivalent of tearing his lung out surgically and he was in desperate pain.

At one point, Tobin gave the jury a literal hands-on description of how we breathe and nine of the jury followed his example by pressing on their own necks.

It may well turn out to be the moment of the trial when the jury itself found out what Floyd must have gone through. Tobin has certainly sharply changed the odds in favor of conviction and has become an overnight hero to many Americans.