The Boston Massacre and the Rule of Law

The moral revolution of ideas behind the American cause originated long before it became a military conflict. As Adams famously observed later in life,

Colonial Americans repeatedly turned to classical authors and English republican thinkers for political guidance. The tradition colonists inherited emphasized a crucial principle: liberty can survive only where law restrains power. Arbitrary authority from any source poses a threat to freedom. Only a system governed by stable and impartial laws can secure liberty.

When Adams stepped forward to defend the British soldiers in 1770, he was acting within a tradition that stretched back nearly 2,000 years.

One of the earliest and most influential articulations of the rule of law appears in Aristotle’s writings. In his work Politics (330 BC), Aristotle argues that “it is more proper that law should govern than any one of the citizens.” Though Aristotle provided the philosophical foundation for the rule of law, the Roman historian Livy later provided historical narratives that inspired future generations. Livy’s monumental history of Rome, Ab Urbe Condita (circa 33-9 BC), traced the city’s rise from monarchy to republic.

One of Livy’s most famous stories describes the overthrow of Rome’s last king, Tarquin the Proud. The tyranny of the royal family provoked a revolution led by Lucius Junius Brutus. The Romans ultimately expelled the monarchy and established a republic built upon the rule of law rather than the personal rule of kings. The Roman Republic created institutions designed to limit authority, including annual elections of representatives, a system of checks and balances, and legal protections for citizens.

Livy’s narrative takes a grim turn when Brutus discovers that his own sons had participated in a conspiracy to restore the Tarquin monarchy. Brutus ordered their execution regardless of their familial status. The lesson? No individual, not even the children of the founder of the Republic, could stand above the law.

During the European Renaissance, scholars rediscovered and reinterpreted Roman history. In the seventeenth century, the Florentine political thinker Niccolò Machiavelli revived Livy’s lessons in his Discourses on Livy (1517). Machiavelli’s work later influenced the English republican writer James Harrington. Paraphrasing both Aristotle and Livy, Harrington famously declared that a republic must be “an empire of laws and not of men.” Adams later wove this motto into the Massachusetts Constitution of 1780 in Article XXX.

Livy’s history helped shape Adams’s moral imagination and popular opinion about justice and the law. By the eighteenth century, the stories of Rome’s legal institutions had become part of the intellectual vocabulary of the American founders.

The Roman statesman Cicero wrote on law and political philosophy; his works have influenced the Western political tradition for nearly two millennia. He was the first thinker in the Western world to ground the legitimacy of the state in the defense of private property. Cicero’s influence extended beyond abstract theory. His practical political knowledge as an orator and statesman, combined with his philosophical knowledge, made him the perfect union of statesman and philosopher and served as a model for American Revolutionaries.

In the Constitution of Liberty (1960) F. A. Hayek singles out Cicero, the driving force behind the Western political tradition of the rule of law:

John Adams studied Cicero extensively from an early age. By the time of the Boston Massacre, Adams was well-​versed in Cicero’s philosophy and legal rhetoric.

In 80 BC, a Roman citizen, Sextus Roscius, had been accused of murdering his father. Though he was likely innocent, the political circumstances surrounding the case were further complicated by Sulla’s dictatorship. Few lawyers were willing to defend him, but a young Cicero accepted the case and successfully demonstrated his client’s innocence without offending Sulla or jeopardizing his future political aspirations.

Like Roscius, Captain Preston and his soldiers struggled to find legal representation. By defending them, Adams followed Cicero’s example of upholding justice even in politically dangerous circumstances. Cicero’s example of navigating political turbulence in arguing an unpopular case undoubtedly guided Adams’s actions.

Similarly, Cicero’s famous defense of Titus Annius Milo in the speech Pro Milone in 52 BC dealt with a politically charged killing in self-​defense. Milo and his followers met Clodius, a Roman gang leader. Words were exchanged, and in the ensuing fight, Milo killed Clodius.

Cicero argued in favor of the general principle of justified self-​defense. He illustrated that there are many cases in which an individual may “put wicked citizens to death,” such as armed thieves. Although Cicero ultimately lost the case, his argument established a powerful legal principle that killing in self-​defense is not murder.

Adams followed Cicero’s example, arguing that though the British soldiers killed protestors, they acted according to justifiable standards of self-​defense. Adams understood how pivotal this case would be for the future standard of the rule of law. Defending the right of self-​defense, Adams exclaimed, “We talk of liberty and property, but, if we cut up the law of self-​defence, we cut up the foundation of both.” Though Cicero was unsuccessful in his defense of Milo, Adams was largely successful. Most of the soldiers were acquitted, while two were convicted of manslaughter and later released.

The classical republican tradition was revived in seventeenth-​century England by writers who opposed absolute monarchy and arbitrary authority. Among the most influential of these figures was the hero of the English Civil War and political theorist Algernon Sidney.

Sidney argued that political authority ultimately derives its legitimacy from the consent of the governed. Sidney’s 1698 Discourses Concerning Government became a foundational text of political theory and the rule of law. Sidney’s ideas gained additional authority from his martyrdom. Accused of treason for his opposition to the Stuart monarchy, he was executed in 1683.

In his speech published after his execution, Sidney succinctly expressed his revolutionary political philosophy:

Adams quoted Sidney’s Discourses in his closing statement to the jury:

Adams’s appeal to Sidney carried a deeper rhetorical significance. Sidney was remembered in the colonies as a martyr of resistance to tyranny, a man executed for opposing arbitrary power. By invoking Sidney not to justify rebellion but to defend the law, Adams cleverly reframed the moment before the jury. If even the rebellious Sidney insisted that law must be “deaf, inexorable, inflexible,” then the passions of the crowd should not determine the fate of the soldiers.

Criminal law prior to the eighteenth century was often unpredictable, harsh, and deeply arbitrary. Judges exercised immense discretion, punishments were frequently disproportionate to the crime, and torture was a common tool for extracting confessions.

This began to change rapidly when the young Italian philosopher Cesare Beccaria, at the age of twenty-​six, published a short treatise titled On Crimes and Punishments (1764). It rapidly became one of the most influential works of the Enlightenment and transformed how many thinkers understood criminal justice.

Beccaria believed laws are best understood as “the conditions whereby free and independent men unite to form society.” From this premise, Beccaria drew two powerful conclusions. First, laws must apply equally to everyone. The obligation to obey the law extends “from the throne to the hovel,” binding both rulers and ordinary citizens alike. Second, laws are legitimate when the punishments for crimes preserve the liberty and security of society. Punishment, in Beccaria’s view, should never be an act of revenge.

Beccaria’s ideas spread quickly throughout the Atlantic world and his work was widely read in Britain and America, where lawyers and political writers frequently referred to it. In the Boston Massacre trials, Adams opened his defense with Beccaria: “If I can but be the instrument of preserving one life, his blessing and tears of transport, shall be a sufficient consolation to me, for the contempt of all mankind.”

Like Beccaria, he stressed that punishment should be guided by clear legal principles and that every accused person deserved a fair trial, regardless of public opinion. Adams’s use of Beccaria reflects the emerging Enlightenment ideal of governance and criminal justice: a system governed by rational rules, procedural fairness, and the equal protection of the law.

For lawyers like John Adams, citing Beccaria helped reinforce the idea that justice must be governed by law rather than passion. Courts exist not to satisfy the anger of the public but to determine truth through reasoned judgment.

When Adams agreed to defend the British soldiers in 1770, he was therefore drawing upon a vast intellectual tradition.

In defending the soldiers and insisting upon a fair trial, Adams’s defense demonstrated that the American resistance to British rule was grounded in a deeper tradition linking law and liberty. Adams helped establish the rule of law as one of the central principles of the American republic.

The Boston Massacre trials show that the intellectual foundations of the American Revolution were already firmly established in the populace in the years preceding the Declaration of Independence. John Adams’s successful defense was not a result of legal originality, but the fidelity to a larger tradition that upheld the importance of the rule of law.

Adams’s defense of the British soldiers demonstrated that the American resistance to British rule was grounded in an intellectual tradition that stressed the harmony between law and liberty. Drawing upon ideas that stretched from Aristotle, Livy, and Cicero to Sidney and Beccaria, Adams insisted that justice must remain impartial. The new republic would claim legitimacy not by abandoning law in the name of revolution, but by upholding it. In that sense, the Boston Massacre trials reveal something essential about the American cause. The nation that emerged from the Revolution aspired to be what Livy, Harrington, and Adams described: “an empire of laws, and not of men.”