The anti-immigrant movement sets great store by “legality.’ “What part of ‘illegal’ don’t you understand?” is one of their favorite taunts.

But we know that it is very easy for any government to create new “illegals”; all it has to do is pass some law forbidding people from doing something that they have been doing out of necessity, maybe for centuries.

In medieval England, it was illegal for hungry peasants to hunt the king’s deer. Deer are deer and hunger is hunger, but add this little law and you have the right to hang half the peasantry.

In Spain in the 1500s, it was illegal to be a Jew or a Muslim.

In the USA in the 19th century, it was illegal to teach slaves’ children to read. Until Rosa Parks made her stand, in many parts of the United States it was illegal for Black people to sit in the front of the bus, or to use the “whites only” washroom.

In South Africa, until the fall of apartheid, it was illegal for African people to move about without a special government pass, to live in “whites only” neighborhoods, or to swim in the vast Indian Ocean at Durban except at special “Natives only” beaches. It had been illegal for them to drink wine or brandy also, until international boycotts began to harm the South African wine and brandy industry, at which point it conveniently became legal again.

All of the above “illegalities” (except the one about the royal deer) have been swept away by history, and not only has the sky not fallen, the world is far better for their disappearance. But at the time, many people might have yelled at people who violated these laws (Frederick Douglass surreptitiously teaching himself to read, for example): “What part of ‘illegal’ don’t you understand?”

So let’s not stand in awe of some little law that some mediocre politicians, out of opportunism, malice, lack of imagination or sheer boredom, choose to pass. Laws, and thus the distinction between “legal” and “illegal,” are political products. Laws passed by the U.S. Congress reflect the political struggles of the moment, and often have as much, or more, to do with posturing for various audiences as with protecting the public interest.

Most often, they are passed to protect the interests of those with the most money and the most power. Such laws sail through the legislative process effortlessly. Laws are passed to protect the rest of us only when we organize and demand them, and then they are usually weak and inadequate (like our labor laws).

Necessity drives poor farmers and workers from Mexico, Central America and the Caribbean to cross our borders and land on our shores. They may bring their families with them, or come with the plan of earning money and sending it back home. They cannot get permanent resident visas because the laws of this country do not allow poor farmers and workers without higher education and without prosperous U.S. citizen relatives to get such visas. But, as a wise Englishman once said, “Necessity knows no law.”

The necessity that makes these poor farmers and workers do this is also the product of laws passed by political mediocrities at home and abroad. These laws have set up international trade rules to favor the rich and powerful.

If you are a peasant, you still can’t poach the royal deer, but if you are a billion-dollar U.S.-based agribusiness, you can dump your corn across the Mexican border well below the price it cost to produce it, and then make the U.S. taxpayers subsidize you not only to make up the difference but also to give you a handsome profit. This outrageous state of affairs ruins the Mexican farmer and robs the U.S. taxpayer, but there is nothing “illegal” about it.

So when a Mexican or Salvadoran or Guatemalan peasant chooses to flout our immigration laws — unilaterally-imposed laws of a foreign power which has never given his or her own country room to breathe — by crossing our border without a visa, let’s not be intimidated by those who shout, “What part of ‘illegal’ don’t you understand?” Instead let’s yell back, “What is it about basic fairness you don’t understand?”

Emile Schepers is an immigrant rights activist.