The so-called sincerity condition, that an agent believes what it communicates, if often specified as a semantic condition on performing a declarative type of speech act in an Agent Communication Language (ACL). We argue that the sincerity condition should not be part of the normative standard semantics of an ACL, although it is useful as an informative guideline for co-operating agents. We can then begin to distinguish the meaning of the declarative performative in isolation from its meaning as used in the context of a conversation. Futhermore, we can begin to appreciate some of the legal implications underlying agent communications.