We, the enlightened cosmopolitan humans of the 21st century, look at this as a human right enshrined in international law. After all Article 13(2) of the Universal Declaration of Human Rights says: "Everyone has the right to leave any country, including his own, and to return to his country."
But the UDHR was only signed in 1948. So does that mean that the "right to leave" is some modern newfangled right that bureaucrats and politicians pulled out of their hats at the end of World War II?
In a 1981 article called "Citizenship and the Right to Leave" a fellow named Frederick G. Whelan looked at where this right originated. Strangely enough he found it (or something that closely resembled it) in the very first version of the Magna Carta - the one King John of England assented to in 1215.
"Liceat unicuique decetero exire de regno nostro, et redire, salvo et secure, per terram et per aquam, salva fide nostra, nisi tempore gwerre per aliquod breve tempus, propter communem utilitatem regni, exceptis imprisonatis et utlagatis secundum legem regni, et gente de terra contra nos gwerrina, et mercatoribus, de quibus fiat sicut predictum est."
"It shall be lawful in future for any one, keeping loyalty to the Crown, to leave our kingdom and to return safely and securely, by land and by water. This is except in time of war, when men may go, only in the public interest, for some short period. (This excludes, always, those imprisoned or outlawed in accordance with the law of the realm, natives of any country at war with us, and merchants, who shall be treated as previously stated.)"
But, as Whelan explained, it disappeared from all further versions including the final one issued by Henry III. He, in fact, "required any subject leaving the country to obtain a license, and other monarchs down to James I regularly issued prohibitions on the exit of important classes of subjects (e.g., clerics, noblemen, soldiers, skilled artisans). Otherwise the restrictions were relaxed in practice, and it came to be understood that anyone could leave unless specifically forbidden, so that travel and emigration were permitted to English subjects as a matter of policy. But the legal authority of the government to forbid this was not doubted, nor did the exercise of this privilege obliterate the allegiance which the emigrant continued to owe to the king."
Roughly 700 years later the "right to leave" gets put on the post-WW II agenda and included as a fundamental right in the UDHR. How did that happen?
Whelan wasn't sure how it came about but he did see Articles 13(2) and 15(2) as something new and radical:
"A right of emigration as a human right is something new in world politics, a claim to which the laws and practice of many states, past and present, have been opposed. It is not only new; it is a radical claim in the fundamental challenge which it at least implicitly poses to the prevailing conception of the authority of the sovereign state and to the world order based on sovereign states, which is legitimized in traditional international law."
"This right in particular, however, by its content, seems to pose a more specific challenge, in that it entirely releases individuals from binding ties of allegiance to their countries, conferring on them full liberty to abandon their nationality at will and assume a new civic identity on a voluntaristic basis. This claim, now put forward as a human right, raises important and basic questions about the nature of a political society and the individual's place within it."
Yes, and for these reasons and many many others we need to take emigration as seriously as immigration.