The blood remained fresh on the snow outside Boston’s Custom House on the morning of March 6, 1770. Hours earlier, rising tensions between British troops and colonists had exploded into violence when a band of Redcoats opened fire on a crowd that had pelted them with not just taunts, but ice, oyster shells and broken glass. Although the soldiers claimed to have acted in self-defense, patriot propaganda referred to the incident as the Boston Massacre. Eight British soldiers and their officer in charge, Captain Thomas Preston, faced charges for murdering five colonists.

Not far from the Custom House, a 34-year-old Boston attorney sat in his office and made a difficult decision. Although a devout patriot, John Adams agreed to risk his family’s livelihood and defend the British soldiers and their commander in a Boston courtroom. At stake was not just the fate of nine men, but the relationship between the motherland and her colonies on the eve of American Revolution.

In the new book John Adams Under Fire: The Founding Father’s Fight for Justice in the Boston Massacre Murder Trial, Dan Abrams and coauthor David Fisher detail what they call the “most important case in colonial American history” and an important landmark in the development of American jurisprudence. Abrams, who is also the chief legal affairs correspondent for ABC News and host of “Live PD” on A&E, recently talked about the case with History.com.

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HISTORY: At the time of the Boston Massacre, John Adams was a patriot grieving the loss of a child with a new baby on the way. Why did he risk his family’s livelihood to represent the British soldiers?

Dan Abrams: The main reason was that he felt everyone was entitled to a defense. But I also think he learned a little about the case and thought there was a legitimate defense—because the events were not as clear cut as some patriots wanted to make them out to be. He also knew there were a couple of attorneys who said they would take the case as long as he was part of the team.

Adams defended the British officer Thomas Preston and his soldiers in two separate trials. Can you talk about the balancing act Adams undertook to defend all his clients without alienating his fellow Bostonians, many of whom fervently supported the broader patriot cause?

In terms of the town, you know, these days criminal defense lawyers regularly cite John Adams’s defense of the British soldiers as the example of why they have to represent certain clients. And yet the thing that Adams did in this case that some of them don’t was to defend them in a way that wasn’t scorched earth. Adams didn’t blame the city for initiating the skirmish. He kept it very, very focused on the facts of this particular instance—what happened, who was there, the specific individuals—and did not make it a broader indictment of the Sons of Liberty and others who had supported violence against the British soldiers.

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The trial featured dozens of witnesses who often gave contradictory testimony. Was it Adams’s legal strategy to make jurors unclear about the facts on the night of the incident?

I don’t think it was part of his strategy to make it unclear. I think it was unclear. There was a lot of confusion about exactly what happened. What we know didn’t happen is what most of us learn in school—this idea of British soldiers mowing down colonists. What exactly led to that first shot being fired is still unclear even today, but I think that Adams had to go a step further here. I think he had to show that these soldiers were in fear, and I think he did.

What was the impact of the testimony of Dr. John Jeffries, who reported that one of the Boston Massacre victims said on his deathbed that the soldiers fired in self-defense?

When you have a doctor saying that one of the victims understood why the soldiers did what they did, there’s almost nothing more powerful. It is hearsay. It is also what is called the dying declaration, and in a courtroom today we have an exception to the hearsay rule for a dying declaration because the theory is that, although hearsay evidence can be typically unreliable, it’s more reliable if it’s someone’s final statement before their death.

Adams wasn’t particularly charismatic, so what made him an effective lawyer?

First of all, I think he truly appreciated the law. I think he had a real love for the law and the primacy of the law. Others may have had more rhetorical flair, but when it came to laying out the facts of the case, particularly in a difficult case, Adams was incredibly smart and effective. Part of what made him effective may have been his lack of pizazz—because he was simply credible as a student of the law.

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What was the impact of these trials on the creation of the American legal system?

What makes this case so interesting from a legal perspective is how they had to figure things out in many ways. Yes, they were using British law, but there was also this sense that the colonists wanted their own system of law, so some of the rules were different. This was the first time reasonable doubt had ever been used as a standard. It was the first time a jury was sequestered. This was definitely a case of firsts.

I think part of the reason certain aspects of this case became enshrined was because this case was viewed in such a positive light historically. At the time, colonists were frustrated at the result, but I think they realized the trial had been fair. And if you can have a case with this much emotion and passion and get a mixed verdict, which was generally unsatisfying to the colonists—and yet have it accepted—that is the kind of case that serves as effective precedent.

Patriots accepted the mixed trial verdicts without violence. What does that say about their faith in the rule of law?

The Boston Massacre certainly could have led to the revolution six years earlier, but it didn’t because people accepted a very controversial verdict. As we talk about in the book, part of the reason the trial transcript was so important was so anyone who wasn’t in court could still review what the witnesses said. It wasn’t just British soldiers haphazardly firing on colonists.

After researching the trials, was justice served in the outcome?

Stunningly so. I think the verdicts are almost exactly what we would see today. It’s obvious to me that Captain Preston didn’t order his men to fire, and he was acquitted. They could have convicted all the soldiers for the actions of one or two of them, but they didn’t—because there simply wasn’t evidence that the others were involved in the shooting. And I think that’s an amazing testament to the jurors of the day.

This interview was condensed and edited.