Disjunctive allegations are allegations in a pleading joined together by an "or". In a complaint, disjunctive allegations are usually per se defective because such a pleading does not put the party on notice of which allegations they must defend.
On the other hand, defendants often plead in the alternative by listing seemingly inconsistent defenses. For example, "I did not do the crime", "if I did, I didn't know", or "even if I did know, I've got a good excuse". Such a pleading may be considered disjunctive and may be permissible. Allegation is always in plural.
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