Martin Luther King, Jr. and Natural Law

Martin Luther King Jr and Natural Law

Martin Luther King Jr and Natural LawOn the third Monday of every January our nation celebrates Martin Luther King, Jr.’s birthday. It was King, more than any other public figure of the past century, who pricked the nation’s conscience concerning the injustice of treating people differently because of the color of their skin.

But while most of us recall King for his efforts as a civil rights leader, few people are aware of the specific reasons why King fought so valiantly for equality before the law. King understood that ideas about individual liberty and civil justice must come from prior assumptions concerning the law. These assumptions are grounded on considerations of what is morally right and, ultimately, on the nature of God.

But sadly, we have forgotten those principles. It’s like we are enjoying the fruit of someone else’s labor, an earlier generation who know how to plant and cultivate the tree of liberty, but we no longer know how to keep the tree alive. We are just living off the fruit as long as long as it will bear. But without constant cultivation, the tree slowly withers and eventually dies. And we no longer know how to plant more trees like it.

What can we learn from King’s fight for justice? Worldview analysis reveals King’s insight into why racial discrimination should not be tolerated. And with that understanding we find the reason for all just laws. If we are interested in keeping liberty alive, we must recover what King knew.

Just Laws and Morality

In the spring of 1963 in Birmingham, Alabama, King led a massive march to bring attention to the widespread segregation and discrimination against black people. King was arrested for his role in organizing the protest without a permit to march in the streets. In jail, King received a letter from several Alabama ministers who questioned why King condoned breaking the law.

King responded with his now famous, Letter from Birmingham Jail.1 In it, King wrote, “One may well ask how can you advocate breaking some laws and obeying others?” The answer, he said, “is found in the fact that there are two kinds of laws: just laws . . . and unjust laws.” King continued, “One has not only a legal but a moral responsibility to obey just laws, but conversely, one has a moral responsibility to disobey unjust laws.”

So far, so good. Most of us can follow King’s reasoning to this point. But this raises the question; how does one determine whether a law is just or unjust? A just law, King wrote, “squares with the moral law . . . . An unjust law is a code that is out of harmony with the moral law.” Wait a minute, this language sounds strange to our ears. How can King equate the law with morality?

Morality and Natural Law

King supported his view by stating that a just law is rooted in “natural law.” What’s “natural law”? Several years ago I asked my lawyer cousin if he had studied “natural law” in law school. After reflecting a moment, he recalled studying that idea in a class on the history of law. That’s interesting, because natural law was the predominant legal theory from the founding of our nation until the mid 1900s. But about fifty years ago law schools shifted their focus and natural law was relegated to the history books. But in King’s day the shift had not yet taken place. He was addressing a concept that most people understood and agreed to.

So what is natural law? Natural law theory begins with the idea that everything has a purpose. We can discern a thing’s purpose by how it’s made. For example, the purpose for the engine in your car is to give the car motion. Every detail about the engine is designed for that purpose. As you study the internal combustion engine, you realize that it takes gasoline, among other things, to fulfill its purpose. You might say there is a rule that describes this reality. We’ll call it the law of the internal combustion engine. The law could be expressed like this: “Internal combustion engines run on gas.” If we cooperate with how the engine is made by putting gasoline in the tank, the engine performs according to its purpose and everything goes well.

On the other hand, if we refuse to cooperate with the law of the internal combustion engine by, say, putting molasses in the tank, the pistons get gummed up and cease to function according to their design and the engine fails to live up to its purpose. We would say this is bad and that we shouldn’t do things like that, especially if the engine happens to be in your car.

Natural law takes this idea of purpose and applies it to humanity. The assumption is that people are made for a purpose. Do you want to know what our human purpose is? One way to find out is to consider how we are made. For example, in the area of our sexuality, it is obvious that males and females are made differently and the difference is for the purpose of continuing the species. Every culture throughout history has acknowledged this difference by placing moral boundaries around marriage. This is to preserve the natural order of producing and raising children.

In fact, this “natural law of marriage” is confirmed in many respects. For example, every study conducted on marriage and the family affirms that when society cooperates with our sexual design by maintaining marriage between a man and women, things go better for everyone in the family as well as for the larger society. Conversely, when we depart from that arrangement, individuals and society suffers.2

The point is that just as there are physical laws that describe how the physical world works, so there are moral laws that describe how we work best in relation to others. As King put it, there are “certain universal principles that are inherent in the moral structure of the universe, and these principles are as inescapable as the law of gravitation.”3 In other words, moral laws cannot be denied. They are as real as gravity!

Likewise, as physical laws are discovered by patient observation, so moral principles discerned through careful thought and inquiry. The moral laws that are discovered from such observation are not arbitrary, but are universally applicable and evident to all reasonable people. This moral law, discovered in the nature of who we are, is called natural law. And when rightly understood, these laws correspond with the moral laws we find in the Bible.

Natural Law and Civil Rights

Martin Luther King did not invent the concept of natural law. It has been around since the Greek philosopher, Aristotle, wrote about the idea over 2,000 years ago. It was further developed by Christian thinkers such as the 5th century Church father, Saint Augustine, and later by philosopher and theologian Saint Thomas Aquinas.

By the 1700s natural law was a staple of British legal theory and found its way into the universities of early America through the writing of the British legal scholar, William Blackstone. From the inception of our nation’s founding, Blackstone’s Commentaries was the primary text for American lawyers and politicians. And Blackstone stressed that for a civil law to be legitimate, it must rest on natural law. Blackstone wrote, “This law of nature . . . is binding over all the globe, in all countries, and at all times; no human laws are of any validity, if contrary to this . . . “4

Martin Luther King echoed Blackstone when he expressed in his letter that a human law is invalid if it contradicts natural law. And the most fundamental law of nature is that all people, regardless of the color of their skin, should be treated as equals by the civil government. Therefore, any civil law must reflect this fundamental natural law.

Civil Rights and God

But there is one more piece to the puzzle that completes the picture of human equality before the law. That is the idea that natural law is rooted in the nature of God. But wait, you might say, isn’t that smuggling religious language into the civil discourse? Aren’t we supposed to keep religion separate from politics and law?

As it turns out, trying to separate religious ideas from political ideas is like trying to separate the oxygen atom from two hydrogen atoms and still have water. It just doesn’t work that way. In the same way, one’s religious ideas cannot be separated from their political fruit. As the Framers of our nation declared,

We hold these truths to be self-evident, that all men are created equal, that they are endowed by their Creator with certain unalienable Rights, that among these are Life, Liberty and the pursuit of Happiness. — That to secure these rights, Governments are instituted among Men.5

Beginning with the Creator, there is a direct line from human equality to human rights to the purpose of government to secure those rights. And all of this is “self evident.” That means that any reasonable person can figure this out by carefully observing nature, i.e., natural law. Jefferson, Madison, Washington, and the rest got it exactly right. They understood the linkage between government and God. As men who were steeped in natural law theory, they believed that there are certain rights that precede the civil law. These rights originate from God, therefore, the government cannot take them away. Jefferson even queried, “can the liberties of a nation be thought secure when we have removed their only firm basis: a conviction in the minds of the people that these liberties are of the gift of God?”6 Jefferson wrote these words in the context of decrying slavery, calling on a just God to remedy the inequality of men owning other men.7

But even though slavery had been abolished in the United States for a hundred years, when King wrote in 1963 there was still injustice and discrimination directed at black Americans. Later that same year, at a rally in Washington, D.C., King cited the call for liberty found in the Declaration of Independence, referring to it as a promise that was made back in 1776 and is now due the black race. He said

When the architects of our republic wrote the magnificent words of the Constitution and the Declaration of Independence, they were signing a promissory note to which every American was to fall heir. This note was a promise that all men, yes, black men as well as white men, would be guaranteed the unalienable rights of life, liberty, and the pursuit of happiness. It is obvious today that America has defaulted on this promissory note insofar as her citizens of color are concerned. Instead of honoring this sacred obligation, America has given the Negro people a bad check, a check which has come back marked “insufficient funds.” But we refuse to believe that the bank of justice is bankrupt. We refuse to believe that there are insufficient funds in the great vaults of opportunity of this nation. So we have come to cash this check — a check that will give us upon demand the riches of freedom and the security of justice.8

Known as his “I have a Dream” speech, King eloquently intoned

I say to you today, my friends, so even though we face the difficulties of today and tomorrow, I still have a dream. It is a dream deeply rooted in the American dream. I have a dream that one day this nation will rise up and live out the true meaning of its creed: “We hold these truths to be self-evident: that all men are created equal.” I have a dream that one day on the red hills of Georgia the sons of former slaves and the sons of former slave owners will be able to sit down together at the table of brotherhood. I have a dream that one day even the state of Mississippi, a state sweltering with the heat of injustice, sweltering with the heat of oppression, will be transformed into an oasis of freedom and justice. I have a dream that my four little children will one day live in a nation where they will not be judged by the color of their skin but by the content of their character. I have a dream today.9

Liberty. Equality. Justice. Martin Luther King did not live to realize his dream, as he was gunned down on April 4th, 1968. But we remember his leadership in making that dream a reality for the next generation, our generation. And more importantly, what needs to be remembered is the worldview that propelled him to act against injustice; the idea that legitimate laws depend on natural law. The legacy that King left us is not just about civil rights, but the deeper understanding that human rights come from the hand of God.


  1., accessed 01/15/2008.
  2. “As social science research data and government surveys increasingly show, the decline in marriage since the 1960s has been accompanied by a rise in a number of serious social problems. Children born out of wedlock or whose parents divorce are much more likely to experience poverty, abuse, and behavioral and emotional problems, have lower academic achievement, and use drugs more often. Single mothers are much more likely to be victims of domestic violence. With the rise in these problems comes high program costs to deal with the effects of the breakdown of marriage. For children whose parents remain married, however, the benefits are real. Adolescents from these families have been found to have better health and are less likely to be depressed, are less likely to repeat a grade in school, and have fewer developmental problems. The implications of such mounting evidence for social policy are immense.” For statistical details, see Patrick F. Fagan,, “The Positive Effects of Marriage: A Book of Charts,” accessed 01/10/2008.
  3. The Martin Luther King, Jr. Reasearch and Education Institute.
  4. William Blackstone, Commentaries on the Laws of England, Introduction, Section 2,, accessed 01/15/2008.
  5. Taken from the Declaration of Independence, accessed 01/15/2008.
  6. Thomas Jefferson, Notes on the State of Virginia (Philadelphia: Matthew Carey, 1794), Query XVIII, pp. 236–237.
  7. Some have questioned Jefferson’s sincerity over his criticism of slavery since Jefferson owned slaves. This is a multi-layered issue. Some insight can be gained from understanding the context of Jefferson’s day. He wrote in 1814, “My opinion has ever been that, until more can be done for them, we should endeavor, with those whom fortune has thrown on our hands, to feed and clothe them well, protect them from ill usage, require such reasonable labor only as is performed voluntarily by freemen, and be led by no repugnancies to abdicate them, and our duties to them.”
  8., accessed 01/15/2008.
  9. Ibid.