Dual Citizenship in Italy: the rules to qualify

In theory, if you meet the qualifications, you are already an Italian citizen and have been since birth.
In the jure sanguinis process, you are not applying for Italian citizenship per se, you are applying for recognition of a citizenship you already have.
However, you must submit the required documentation to the Italian Consulate proving that your ascendants were Italian citizens and transmitted citizenship down the line.
Ultimately, the decision of whether or not you prove your case is theirs.
Below are the different categories that determine if you qualify for recognition.

Category n. 1

Your father was born in Italy and was an Italian citizen at the time of your birth.

Category n. 2

Your mother was born in Italy and was an Italian citizen at the time of your birth, you were born after January 1st, 1948

Category n. 3

Your father was born outside of Italy, your paternal grandfather was born in Italy and was an Italian citizen at the time of your father’s birth.

Category n. 4

Your mother was born outside of Italy, your maternal grandfather was born in Italy and was an Italian citizen at the time of your mother’s birth, you were born after January 1, 1948.

Category n. 5

Your paternal or maternal grandfather was born outside of Italy, your paternal or maternal great grandfather was born in Italy and was an Italian citizen at the time of your paternal or maternal grandfather’s birth.
The Disqualifiers
Unfortunately, there are some rules that prohibit some from being recognized as Italian citizens.
1. Prior to March 17, 1861, Italy was not a unified country. This means that before this date, there was no Italy and, therefore, there were no Italian citizens. In order to qualify, the Italian ancestor in your line must have been born after this date.
2. The 1912 Rule. Italian citizens naturalized before July 1, 1912 could not transmit citizenship to their children even if they were born before their naturalization.
3. The 1948 Rule. A person born before January 1, 1948 can claim Italian citizenship only from his/her father (who was not a naturalized citizen of another country before his/her child’s birth), and a woman can transfer citizenship only to her children born after January 1, 1948 if she was not a naturalized citizen of another country before her child’s birth.
4. One of your ascendants formally renounced their Italian citizenship in front of an Italian Consular, diplomat or government official.
Some people have legally challenged these Rules.
If you choose to challenge, you will likely need a lawyer.

Here’s an example of a typical case:
Mary is applying for Italian citizenship. Her grandfather, Francesco, came to the U.S. from Italy in 1920 and in 1926 had a child, Luigi (Mary’s father). Francesco naturalized and became a U.S. citizen in 1930. Luigi is a U.S. citizen because he was born in the U.S. He is also an Italian citizen because Francesco was still an Italian citizen at the time of Luigi’s birth. Luigi did not lose his Italian citizenship when his father naturalized and he never renounced his Italian citizenship. Because Luigi was an Italian citizen at the time of Mary’s birth, it makes Mary eligible for Italian citizenship jure sanguinis. If Francesco had had a child after he naturalized in 1930, the descendants of that child would not be eligible for Italian citizenship jure sanguinis.

If you fall within one of the categories and are not affected by any of the disqualifying rules, you may want to explore further.