An ECI is a "very official" form of petition, run by the European Union itself. If it is successful, the European Commission (npub1m96…ag4y) has a legal obligation to respond with an official act. Additionally, the European Parliament organizes a hearing centered on the petition, and might (but it is far from certain) also discuss it in plenary.
https://citizens-initiative.europa.eu/how-it-works_en
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