Occasionally, rarely, courts will illuminate, rather than obscure, the truth. In this opinion, the court of appeals articulated the best definition I have ever seen of when a half-truth becomes deceptive. In sum, the Court stated that half-truths become untruths when they would lead to the inference different than that that would follow had the whole truth been told. The full opinion can be read here:
http://www.kscourts.org/Cases-and-Opinions/Opinions/CtApp/2011/20111021/104318.pdf