I'm no expert, but that doesn't sound right. Specifically, it contradicts my model of Anglo-American jurisprudence, where I expect:
1) Defendants have the right to a trial, regardless of how "obviously guilty" they are in anyone's eyes.
2) Trials are, in part, about whether the state has met its burden to prove the elements of the case, regardless of the lay truth of the accused's guilt. [A]
3) Given the above, the work of a lawyer (in a trial) does not inherently involve the representation that "this defendant is innocent", but only that "there is insufficient evidence of that element of the case", which needn't be a fraud on the court, even if the prosecution's claim is true.
(With that said, more specific lies can be off limits.)
[A] A Man for All Seasons: "The world must judge according to its wits; this court must judge according to the law."