What are they plotting against? "Ernani o l'onore castigliano"

Speranza

In Victor Hugo, "Don Carlo" has raped wives. (One of the conspirators wishes to avenge the honour of his wife impugnated by the libertine Don Carlo).

In Piave's libretto, the conspiracy lacks precise motivation.

Don Carlo is generally guilty of having violated 'the rights' of the 'Iberica contrada'.