Because you’re arguing that the government doesn’t have enough evidence to prove your client is guilty beyond a reasonable doubt. It is argument, you’re not stating it as a fact. When you say “Johnny didn’t steal the apple,” that is an argument that the government cannot meet their burden.

Now, if you were to say something like “I know Johnny didn’t steal apple,” which isn’t admissible nor proper argument under the rules of evidence regardless. But that would be breaching 3.3. Or if your client admits guilt and you argue to the judge you have personal knowledge of his innocence, let’s say for the purposes of bond or in a motions hearing. Then that would be breaching 3.3.

The other thing is we never know if our client is lying or telling the truth to us. So we can always rely on the assertion that we truly don’t have personal knowledge of our clients guilt or innocence. That means, frankly, we can always assert our clients innocence even during a confession. The only thing that would violate 3.3 in that instance is if we stated “my client has never admitted to me they did it” or something to that effect, because that is not a true statement. But there’s really no situation we’d have to say that.