I have noticed that while many constitutions guarantee voting rights for its citizens, these provisions are often phrased in a way that does not preclude expanding such right to people beyond the explicitly stated demographic.
A common way of phrasing it would be: "X has the right to vote..." rather than "ONLY X has the right to vote..."
Here are some examples:
Every Swedish citizen who is currently domiciled within the Realm or who has ever been domiciled within the Realm, and who has reached the age of eighteen, is entitled to vote in an election to the Riksdag.
An Estonian citizen who has attained eighteen years of age has the right to vote.
Any person who has attained the age of eighteen shall be entitled to vote; any person who has attained the age of majority may be elected.
In these cases, the provisions seem to imply an inclusive attitude - rather than an exclusionary attitude - towards suffrage, so would it be constitutional for the respective countries to pass legislations that grant voting rights to people beyond what is explicitly mentioned? Such as:
- Permanent residents
- People who have attained 16 years of age
It would also be interesting to know whether some countries have actually passed legislations to test this theory.