Good question.

That's what people say when they don't have an answer yet.

And such is the case with the question in the headline.

I started wondering about it following  a tweeted response by Raouf Eldeeb (@raouf777) to Privacy is Personal:

It is also a fundamental right, not a privilege to be bestowed on anyone. The individual should have the right to determine the extent of his privacy.

While I agreed automatically with both of Raouf's points, I began to wonder about all kinds of rights, including privacy. That's because I was haunted by what Yuval Noah Harari says about rights in his book Sapiens—A Brief History of Humankind (Harper, 2011, 2104):

Sapiens rule the world, because we are the only animal that can cooperate flexibly in large numbers….We cooperate effectively with strangers because we believe in things like gods, nations, money and human rights. Yet none of these things exists outside the stories that people invent and tell one another. There are no gods in the universe, no nations, no money and no human rights—except in the common imagination of human beings….

That's in Chapter 2. In Chapter 6, he also challenges the concept of equality, which informs much of our thinking and lawmaking around rights:

Is there any objective reality, outside the human imagination, in which we are truly equal? Are all humans equal to one another biologically? … Equally, there is no such thing as rights in biology. There are only organs, abilities and characteristics. Birds fly not because they have a right to fly, but because they have wings.

And yet, while Harari says rights are a collection of stories we tell ourselves, he also credits the role of belief in rights for holding civilization together and for advancing it. He points out, for example, that the story of rights America's founders told in the Declaration of Independence was a helluva lot more civilized than the Code of Hammurabi, which applied the death penalty to a huge roster of crimes (including lying), and codified women and slaves as forms of property. Harari also adds that the United States "would not have lasted 250 years if the majority of presidents and congressmen failed to believe in human rights". 

Belief is the thing. And belief, like our species, evolves. One example is how US has evolved away from its prejudice against Native Americans, which the Declaration of Independence calls “the Inhabitants of our Frontiers, the merciless Indian Savages, whose known Rule of Warfare, is an undistinguished Destruction, of all Ages, Sexes and Conditions.” It should also help to recall that slavery and absent suffrage for women were both lawful to the US Constitution when it was ratified in 1789. Slavery ended with the 13th Amendment in 1865, but only after the country suffered through the Civil War. Equal protection for women arrived three years later with the 14th Amendment. Women's suffrage didn't arrive until 1919, with the 19th Amendment. (To put that in a personal perspective, my own grandmother couldn't vote until she was 37 years old, and she made sure her grandkids knew it.)

Neither the Declaration of Independence nor the US Constitution mention privacy at all. (Though the Declaration does mention "certain inalienable rights"—note the plural—which at least should include privacy. Thanks to dwest in his comment below for pointing that out.). Louis Brandeis and Samuel D. Warren pushed the topic to the legal fore with a landmark paper titled "The Right to Privacy" (Harvard Law Review Volume 4 #5, December 1890). What they say in that paper about privacy invasions by photographers and newspapers foreshadows concerns about the same by mobile phone cameras and social media today—and to business models that are just as oblivious to privacy:

Recent inventions and business methods call attention to the next step which must be taken for the protection of the person, and for securing to the individual what Judge Cooley calls the right “to be let alone.”10 Instantaneous photographs and newspaper enterprise have invaded the sacred precincts of private and domestic life; and numerous mechanical devices threaten to make good the prediction that “what is whispered in the closet shall be proclaimed from the house-tops.” For years there has been a feeling that the law must afford some remedy for the unauthorized circulation of portraits of private persons; 11 and the evil of the invasion of privacy by the newspapers, long keenly felt, has been but recently discussed by an able writer.12 The alleged facts of a somewhat notorious case brought before an inferior tribunal in New York a few months ago,13 directly involved the consideration of the right of circulating portraits; and the question whether our law will recognize and protect the right to privacy in this and in other respects must soon come before our courts for consideration.

Of the desirability—indeed of the necessity—of some such protection, there can, it is believed, be no doubt.

Toward that protection, they conclude that privacy is personal:

Still, the protection of society must come mainly through a recognition of the rights of the individual. Each man is responsible for his own acts and omissions only. If he condones what he reprobates, with a weapon at hand equal to his defense, he is responsible for the results. If he resists, public opinion will rally to his support. Has he then such a weapon? It is believed that the common law provides him with one, forged in the slow fire of the centuries, and today fitly tempered to his hand. The common law has always recognized a man's house as his castle, impregnable, often even to its own officers engaged in the execution of its commands. Shall the courts thus close the front entrance to constituted authority, and open wide the back door to idle or prurient curiosity?

We can trace that common law to Cicero (106–43 BCE), who wrote, “What more sacred, what more strongly guarded by every holy feeling, than a man's own home?” The castle metaphor we owe to William Blackstone (1723–1780 CE), in Book 4, Chapter 16 of his Commentaries on the Laws of England, where he writes, “And the law of England has so particular and tender a regard to the immunity of a man's house, that it stiles it his castle, and will never suffer it to be violated with impunity: agreeing herein with the sentiments of ancient Rome…” Today we call this The Castle Doctrine.

You'll find that doctrine present in the United Nations' Universal Declaration of Human Rights, which was drafted in 1948. The Right to Privacy is #12 (of 30) on the UN's official list, and reads:

Nobody should try to harm our good name. Nobody has the right to come into our home, open our letters, or bother us or our family without a good reason. 

With that in mind, let's go back to Brandeis and Warrens' paper. When you read this next passage, think about how it applies to the online world today:

Gossip is no longer the resource of the idle and of the vicious, but has become a trade, which is pursued with industry as well as effrontery. To satisfy a prurient taste the details of sexual relations are spread….To occupy the indolent, column upon column is filled with idle gossip…solitude and privacy have become more essential to the individual; but modern enterprise and invention have, through invasions upon his privacy, subjected him to mental pain and distress, far greater than could be inflicted by mere bodily injury. Nor is the harm wrought by such invasions confined to the suffering of those who may be made the subjects of journalistic or other enterprise. In this, as in other branches of commerce, the supply creates the demand. Each crop of unseemly gossip, thus harvested, becomes the seed of more, and, in direct proportion to its circulation, results in a lowering of social standards and of morality. Even gossip apparently harmless, when widely and persistently circulated, is potent for evil. It both belittles and perverts. It belittles by inverting the relative importance of things, thus dwarfing the thoughts and aspirations of a people. When personal gossip attains the dignity of print, and crowds the space available for matters of real interest to the community, what wonder that the ignorant and thoughtless mistake its relative importance….Triviality destroys at once robustness of thought and delicacy of feeling. No enthusiasm can flourish, no generous impulse can survive under its blighting influence.

Thus, we should not be surprised that Louie and Sam's definition of privacy—”the right to be let alone”—is now coded into the EU's General Data Protection Regulation (GDPR), which was written in 2016, became enforceable in 2018, and is aimed straight at the tracking-based advertising business that pays for much (probably most) of the “blighting influence” we suffer on the web today—and on our phone apps as well.

Today, the story we're telling about our right to privacy is mostly about privacy laws (such as the GDPR and California's AB 375) and their effects—especially on companies that need to comply. It's an interesting story, but one that distracts us away from work that needs to be done. 

The work we need to do most is on tech that gives each of us ways to guard our private spaces and signal to others what's okay and what's not okay.

Privacy as a right is a necessary concern of lawmakers and regulators. But for hackers, the job is making privacy real in the online world. Laws alone won't do that job.