While the Supreme Court might be baffled as to why the census must ask about citizenship, history shows that the citizenship question has been one of common sense. It is, after all, the only way to determine who actually has the fullest rights and privileges afforded to a nation’s people, and nations for thousands of years have asked the question to its people because of how necessary it is for basic governmental functions.

Montesquieu, in his influential Spirit of Laws, traces the ideas of a census throughout history. In it, he marks how the census was used by different governments to determine the privilege and responsibilities of different classes of people. In chapter 7, he discusses the Ancient Greek use of a census:

In Plato’s republic, luxury might have been exactly calculated. There were four sorts of censuses or rates of estates. The first was exactly the term beyond poverty, the second was double, the third triple, the fourth quadruple to the first. In the first census, luxury was equal to a cipher; in the second to one, in the third to two, in the fourth to three: and thus it followed in an arithmetical proportion.

Since land was tied to citizenship and the rights of individual, determining the amount of property and wealth one had was a way to determine political privilege and rights. This also determined the level of taxation, as he points out in a footnote:

The first census was the hereditary share in land, and Plato would not allow them to have, in other effects, above a triple of the hereditary share.

By determining how much wealth and power a certain class of individual had, Plato argued that they would then have to pay a certain amount in taxation. Thus, counting people had both a taxation purpose and a representation purpose, both of which are reflected in the United States Constitution.

As Montesquieu, in the 15th chapter, points out, Ancient Rome divided people based on what class they held, which included various levels of having the rights of citizenship:

At Rome, where they had so many freedmen, the political laws with regard to them were admirable. They gave them very little, and excluded them almost from nothing: they had even a share in the legislature, but the resolutions they were capable of taking were almost of no weight. They might bear a part in the public offices, and even in the dignity of the priesthood; but this privilege was in some sort rendered useless by the disadvantages they had to encounter in the elections. They had a right to enter into the army; but they were to be registered in a certain class of the census before they could be soldiers. Nothing hindered the freedmen from being united by marriage with the families of the free-born; but they were not permitted to mix with those of the senator. In short, their children were free-born, though they were not so themselves.

The census was necessary to determine how many people had what level of right and what level of taxation under Roman law. If one were not registered as a citizen, there were serious consequences, as he explains in Chapter 27:

What kind of citizens then must those have been, who were not registered in the census in which all the freemen of Rome were included? According to the institution of Servius Tullius, mentioned by Dionysius of Halicarnassus, every citizen not enrolled in the census became a slave; even Cicero himself observes that such a man forfeited his liberty, and the same thing is affirmed by Zonaras.

The use of the census to determine slave and citizen was of the utmost necessity to the Romans, and there were those who would avoid paying taxes levied on the different tiers of citizen, including a substantial inheritance tax, by giving up their rights and listing themselves as the lowest level under the census:

they who were not enrolled in one of these six classes, or who were not ranked by the censors among such as were called rarii, were not included in the census according to the spirit of Servius’ institutions. Such was the force of nature, that to elude the Voconian law fathers submitted to the disgrace of being confounded in the sixth class with the proletarii and capite censi, or perhaps to have their names entered in the Caerites tabul.

Only a rare few could experience an economic gain from not being counted as a citizen, and it came at a great social cost. Such was the power and weight of the Roman census and the effect it had on all people under the jurisdiction of Roman law.

In Chapter 30, Montesquieu then analyzes how the use of the term “census” was transformed by later Germanic governments to determine who would pay which taxes and how much. The census, though, was mostly based on a loose sense of the Roman census and targeted only those who would pay taxes:

what they called census at that time was a tax raised upon the bondmen. This I prove by a formulary of Marculfus containing a permission from the king to enter into holy orders, provided the persons be freeborn, and not enrolled in the register of the census. I prove it also by a commission from Charlemagne to a count whom he had sent into Saxony, which contains the enfranchisement of the Saxons for having embraced Christianity, and is properly a charter of freedom. This prince restores them to their former civil liberty, and exempts them from paying the census, It was, therefore, the same thing to be a bondman as to pay the census, to be free as not to pay it.

In essence, the Germanic census was a count of who would pay which taxes and how much, and the only ones that would not be counted in the categories are those exempt. Thus, the Germanic system determined who was restricted under their laws through the system of a census, though it was done in an opposite fashion. Montesquieu continues,

By a kind of letters patent of the same prince in favour of the Spaniards, who had been received into the monarchy, the counts are forbidden to demand any census of them, or to deprive them of their lands. That strangers upon their coming to France were treated as bondmen is a thing well known; and Charlemagne being desirous they should be considered as freemen, since he would have them be proprietors of their lands, forbad the demanding any census of them.

Thus, Charlemagne instituted, through the census, a determination that someone was not of his lawful jurisdiction and would not be counted as part of the census. This, of course, was to the benefit of said individuals because the census had a direct taxing purpose, but it also represented the nature of being part of a nation in both its benefits and its responsibilities.

In these three different cultures that all greatly influenced the founding of the United States, the census was used to determine the rights of the individual people within the territory while also ensuring that they paid the proper amount for their government.

There are substantial differences in citizens, lawful resident, and illegal immigrants in their rights and their responsibilities, and this is both political and economic. States need to know who is a true resident within their jurisdiction both to levy taxes on them and to ensure that only those who are rightfully within their jurisdiction are lawfully present.

This, however, is more than just something that affects illegal immigrants, because many people “live” in multiple states and claim residency in only one. To know the true residency of an individual and where they pay taxes is absolutely necessary to apportion out the appropriate funds for to that jurisdiction. Thus, everyone receives what they are owed and pay what they owe, which is the purpose of the census for thousands of years.