Judge Andrew Napolitano has incensed critics of immigration with his defence of the idea of immigration as a natural right:

Since the freedom of speech, the development of personality, the right to worship or not to worship, the right to use technologically contemporary means for self-defense, the right to be left alone, and the right to own and use property all stem from our humanity, the government simply is without authority to regulate human behavior in these areas, no matter what powers it purports to give to itself and no matter what crises may occur. Among the rights in this category is the freedom of movement, which today is called the right to travel.

The right to travel is an individual personal human right, long recognized under the natural law as immune from governmental interference. Of course, governments have been interfering with this right for millennia. The Romans restricted the travel of Jews; Parliament restricted the travel of serfs; Congress restricted the travel of slaves; and starting in the late 19th century, the federal government has restricted the travel of non-Americans who want to come here and even the travel of those already here. All of these abominable restrictions of the right to travel are based not on any culpability of individuals, but rather on membership in the groups to which persons have belonged from birth.

Americans are not possessed of more natural rights than non-Americans; rather, we enjoy more opportunities to exercise those rights because the government is theoretically restrained by the Constitution, which explicitly recognizes the natural law. That recognition is articulated in the Ninth Amendment, which declares that the enumeration of certain rights in the Constitution shall not be used by the government as an excuse to deny or disparage other unnamed and unnamable rights retained by the people.

So, if I want to invite my cousins from Florence, Italy, to come here and live in my house and work on my farm in New Jersey, or if a multinational corporation wants the best engineers from India to work in its labs in Texas, or if my neighbor wants a friend of a friend from Mexico City to come here to work in his shop, we have the natural right to ask, they have the natural right to come here, and the government has no moral right to interfere with any of these freely made decisions.

I agree with Napolitano. Giving the state the power to restrict freedom of movement is a dangerous precedent, and a dangerous concentration of power. Powerful and well-connected groups and industries can use the largesse of the state to protect their own uncompetitive ventures by restricting immigration.

And why should the state have the power to determine who can and who cannot live where? Surely market forces are a better determinant of the need for workers and migration than a central planner setting migration targets based on their own dislocated criteria?

These are by no means the most significant arguments for the freedom of movement. Ludwig von Mises theorised:

This is a critical dynamic. If a government enacts laws that are undesirable, workers (if they can) will move to another jurisdiction with more desirable laws. Freedom of movement is the status quo today for capital — under the current global regulatory framework, the free flow of capital means that governments have to compete to attract capital from around the globe. Governments do not have to do the same thing for labour, as the flow of immigration is very restricted compared to the flow of capital. This disparity may well have contributed to the extant reality that around the world — but particularly in the United States — capital’s share of output is increasing, while labour’s share is shrinking. Freer immigration could change all that.

There are various misconceptions of immigration. Perhaps most prominent is the idea that immigrants cost natives jobs. But the evidence suggests that this is not true. Eduardo Porter notes:

For years, economists have been poring through job market statistics looking for evidence that immigrants undercut less-educated Americans in the labor market. The most recent empirical studies conclude that the impact is slight: they confirm earlier findings that immigration on the whole has not led to fewer jobs for American workers. More significantly, they suggest that immigrants have had, at most, a small negative impact on the wages of Americans who compete with them most directly, those with a high school degree or less.

Meanwhile, the research has found that immigrants – including the poor, uneducated ones coming from south of the border — have a big positive impact on the economy over the long run, bolstering the profitability of American firms, reducing the prices of some products and services by providing employers with a new labor source and creating more opportunities for investment and jobs. Giovanni Peri, an economist at the University of California at Davis, estimated that the wave of immigrants that entered the United States from 1990 to 2007 increased national income per worker by about $5,400 a year on average, in 2007 dollars. He also concluded that the wave had a small positive impact on the average wage of American workers, by lifting the overall economy. If immigrants hurt anyone, it was the previous cohort of immigrants, with whom they most directly compete in the labor market.

Recent estimates have concluded that a liberalisation of global immigration policies could lift global GDP significantly. More importantly, empirical studies have confirmed the reality that immigration eases the fiscal balance — helpful for developed countries with ageing populations and a shrinking tax base. A 2011 report by Madeleine Zavodny of the American Enterprise Institute found that immigrants on average pay much more tax than they consume in government services:

This means that one frequent objection to immigration — that immigrants overstretch government programs and infrastructure — is irrelevant. Working immigrants pay more than enough in taxes to fund their own costs — often many times over.

The study also found that rather than taking up jobs, each immigrant worker generated jobs for the native population. The supply of work is not fixed. Each additional 100 H1-B workers were found to have generated 183 new jobs for the native population, and each 100 additional H2-B workers generated 464 new jobs for the native population.

But what about the countries that immigrants leave behind? Surely the countries left behind by thousands or millions of workers will fall into recession? Well, perhaps to some extent — although not so much in countries with higher birth rates or slack employment — but that’s the point. Countries that suffer a labour drain may have to reform their legal and political structure to attract workers. This alone would significantly boost competitiveness in the long run. And emigrants frequently send money back to their country of origin, and acquire new skills while working abroad that they can bring back home, in turn enriching their home country.

On the other hand, it might be unwise for countries to immediately switch from a restrictive policy to an open-door immigration policy. While freedom of movement is an essential economic freedom, a radical change in policy could prove destabilising, and cause significant cultural and social dislocation, friction or ghettoisation. Such a large change in policy should be undertaken slowly and cautiously — it would be unwise for governments to rush forward with policies that are unwanted and unpopular with the wider population.

But in the long run, though, the benefits of freedom of movement are clear, and will likely become clearer in the coming decades as more countries and blocs experiment with freer migration policies.