The right to vote must be seen as the right to participate in public affairs in a direct way.  Therefore, such a right has to be enacted at the highest legal level (in the Constitution, for instance) in the most important.  The right to vote has to be seen as very important constitutional right in any constitutional democracy.  A majority of Constitutions around the world, set the minimum age from which citizens will be entitled to vote, either in general elections, or in indirect electoral processes.  Both Constitution and enacted laws can regulate other requirements demanded from voters to be entitled to vote. 

Nowadays, there are some common requirements which must be met in order to allow an individual to execute her right to vote.  Among such requirements we can list some as follows: the age, the citizenship, the entitlement to civil and political rights.  Sometimes, to have a demographic registration in due time has to be considered as a necessary requirement as well.  Such is also the case with the address of the voter at voting-day.  It is clear, however, that any extra requirement can not be discriminatory. 

1. Citizenship

Usually, citizenship presupposes the existence of nationality seen as a legal connection between an individual and a State.  Such a connection represents a requirement demanded from voters which has a historic justification.  To be part of a political community allows citizens to participate in public affairs. 

Nationality and citizenship are not always twin concepts: such a distinction is important for those States in which inhabitants and citizens have different nationalities, because they have different historical backgrounds, different cultural backgrounds, and different political backgrounds. Besides, it is also important to remember that many times citizenship presupposes adulthood. A distinctive characteristic of a State is based on how sovereign it is, and to develop such a characteristic it is necessary to know who can be seen as citizens. Such a determination is usually developed by both the Constitution, and the laws.  Both of them have to determine in a precise way who is a citizen, according to rules based on the place of birth, the age, and other elements.  Both of them have to establish, therefore, what other requirements have to be met in order to get the nationality or the citizenship: to be considered as a legal resident in the country, the relation between the alien and the new country, marriage, parenthood and other legal connections to some nationals, and so on.   

Bearing this in mind, it can be claimed that citizenship is a legal concept, not a political one: both the Constitution and the laws of each single country say when someone can be considered as a national.  In some countries, citizenship is not enough, though (especially when citizenship has been acquired in a particular moment, and by on grounds different to birth) to execute the right to vote.  Usually, in such cases, to live for a while in the country where the election is going to take place, has also be established as a requirement. 

The immediate relation linking citizenship to the right to vote, has lost some ground, sometimes as a consequence of historical, and cultural reasons, on the one hand, or as a consequence of other reasons such a migration, or the commands derived from international treaties. 

Usually, when legal provisions are not set down legally, foreigners are allowed to vote in municipal elections.  Behind such an authorization a powerful reason can be found: legal foreigners do participate in the daily life as any other individual does.  Besides, municipal elections do not have a very influential political scope. The Treaty of the European Union of 1992, for instance, endorses the right to vote and the right to be voted for local posts in all the Union’s countries.  In respect to such a right some precedents can be found in Denmark, Sweden, and Norway.  The British case is quite interesting. There, citizens of the Irish Republic and the Commonwealth have also a right to vote in the British Elections.   

Likewise, it is important to mention the regulation of the election of members to the European Parliament.  Such regulation pioneered many efforts which can be seen as typical in our days. (cfr. The Election of Members to the European Parliament).  There, European citizens are allowed to vote whatever their residence might be.  They also can be voted when their names appear in ballots voted in a European country different to theirs.

Many conflicts can arise from nationality regulations.  Such is the case which some of the former Soviet Republics are facing today (cfr.  The Minorities Excluded from the Right to Vote in , and the Difficulties to be a Russian National). The restriction of citizenship to individuals of certain countries (from both a historical and a cultural point of view) has curtailed the right to vote of many different individuals. 

2. Residence

An individual’s residence can be relevant from two different points of view.  First, foreign citizens can have a right to vote in an alien country’s local elections (they can even get the citizenship of the country in which they reside). Secondly, living in a foreign country can have a detrimental effect on foreign residents.

The place of residence is very important for local or regional elections, and it can even be very important for the electoral registration.  In some cases, particularly in those related to advanced democracies, citizens can vote in regional or national elections living abroad. In such case, electoral laws allow them to send their votes by mail, to vote in their consulates, or to vote in other places (as the right of soldiers, or diplomats living abroad). There are, however, some countries in which such is not the case.  Voting abroad is very important for countries affected by massive and critical migrations.  

Some experiences can make irrelevant where the actual voting takes place.  In Costa Rica, for instance, votes can be drafted in ATM Machines.  It is worth to mention, however, that the places in which voters do live is very important to determine the electoral territory (not the voting point) in which her vote will be counted. The Electoral Registrar allow to draw clear borders bringing electoral territories apart from each other, which is important to determine what kind of election is going to be impacted by voters. 

3. Age

The age requirement to vote has followed the evolution towards universal enforcement of the right to vote.  From a historic point of view, the age to vote has not matched the age to be punished for a crime.  As a matter of fact, voters (around 25 years) were older than criminals.  Different voting ages was established for women.  In our days, however, the great majority of nations have set down that young individuals of eighteen years are citizens and can vote. 

Usually the age to vote is determined in the Constitution, for it represents a limitation against a fundamental right.  Even though countries differ in respect to how old a person can be to be held accountable for a crime, there is a universal trend towards identifying adulthood to civil rights at eighteen years old. 

4. Using fully both civil and political rights.  

Individuals have to be fully entitled to civil and political rights to vote.  Such full entitled can be assumed, until evidence showing them as cancelled, is brought along.  Therefore, the grounds and the procedures which will be used either to cancel or to suspend the use of civil and political rights have to be clearly established and specified in due time. 

5. Limiting the right to vote.

Individuals have a constitutional right to vote and a constitutional right to be voted.  However, the use of such rights can be prevented on conditions which have to be set down on democratic regulations, and which can be listed as follows:

• First of all, since we are dealing with a limitation of fundamental rights, a fundamental principle must be honored: every single limitation imposed on fundamental rights has to be previously established under the law.
• Besides, laws restricting fundamental laws must be interpreted in a very strict and constrained way.  Analogical reasoning is not a valid method of interpretation when fundamental rights are at stake.  
• The upholding of fundamental rights has to be preferred to any other consideration.  In respect to electoral issues, interpretations favoring a full participation of citizens are better than others.  
• They must be applied in a non-discriminatory way.  In other words, in the face of identical situations, identical limitations will be applied, without any personal consideration whatsoever.
• Limitations to the right to vote must aim at the achievement of a free and more democratic electoral process.  Limitations imposed on both the right to vote and the right to be voted, individual sacrifices, are justified as long as they produce a more successful execution of the right to vote or of the right to be voted from a collective point of view. 

There must be an independent authority empowered to control decisions related to limits imposed on fundamental rights.  Usually such authority can be identified with the electoral authority or with the Judicial Branch of Government.  Anyway, any limitation imposed on fundamental rights must be judicially reviewed.