What is the most effective right of confrontation of a witness against a defendant?

There can be no doubt that, from a defendant's standpoint, the most effective right of confrontation of a witness occurs when (1) a witness is under oath, (2) he is subject to cross-examination when he testifies about Facts observed and (3) his demeanor can be observed by the fact finder who must determine his credibility. But certainly neither the federal nor the state constitutional right of witness confrontation guarantees the Most effective right of a defendant to be confronted by witnesses against him. (See California v. Green, supra.) Such a rule of constitutional law would prohibit the introduction of all hearsay evidence and abolish all of the exceptions to the hearsay rule. California v. Green made it clear that, insofar as the federal Constitution is concerned, in guaranteeing the right of witness confrontation, the states were not precluded from creating new exceptions to the hearsay rule, in addition to using those exceptions already in existence.