Every state has nearly the same ethics rules based on the Model Rules of Professional Conduct. An attorney has duties to the court in addition to duties to her client. There is a difference under the law between a "fact" and an explanation or argument. You are not allowed to misstate a fact - that is, a piece of evidence. You are free, within reason, to offer explanations or doubt concerning the truth of that particular piece of evidence. Criminal defense attorneys spend much of a case attempting to demonstrate why a fact introduced by the prosecution should not be accepted as truthful or accurate by the jury.
That's where many of the "aliens did it" arguments come in. Say the prosecution introduces the murder weapon, a Wusthof knife. The prosecution then introduces evidence that the defendant purchased a Wusthof knife in the week before the crime. The defense might introduce evidence subpoenaed from local stores that 75 people within a 100 mile radius also purchased Wusthof knives in the two weeks before the crime. The defense might introduce evidence that other people who were questioned in the investigation also own the same knife. The defense isn't stating that the defendant doesn't own a Wusthof knife, they are attacking the probative value of the fact.
