Does the State have to know about perjury
One of the common complaints I see from defendants is that one or more of the witnesses against them committed perjury. That generally means that they didn't testify in a manner favorable to the defendant. A common occurrence is where two witnesses disagree about a particular fact - the defendant claims the unfavorable witness committed perjury.
Perjury does occur - probably with some regularity. But it is one of the most difficult claims to prove. You need compelling evidence to establish that someone testified falsely.
Even if you can establish perjury, the rule has always been that you must still prove the State/government was aware of it. In legal jargon, the claim is the knowing use of perjured testimony, which is a due process violation. A witness may perjure themselves, but unless you can prove the State knew about it, you are generally out of luck.
The Court of Criminal Appeals may have just changed the law on this claim - at least in limited circumstances. The case is Ex Parte Chabot., No. AP-75,940 (12/09/09). Chabot was convicted of murder, and the main witness against him was an accomplice, Gerald Pabst. He claimed he was an unwitting participant, and didn't leave because he was scared of Mr. Chabot. The victim was sexually assauted, and of course Pabst denied having anything to do with that.
Mr. Chabot was able to obtain DNA testing long after he was convicted, and lo and behold it turns out the person who did the sexual assault was Pabst. Therefore, he perjured himself at trial; arguably the state didn't know it, because they believed Pabst when he said he didnt do it.
The court found Chabot's due process rights were violated because his conviction and sentence was "most likely based on perjured testimony." In truth, the only substantive testimony against Chabot came from Pabst.
The court implicitly recognized that if Pabst perjured himself about committing the sexual assault then maybe he also perjured himself about Chabot committing the murder. The case would have been an easy one if Mr. Chabot had been charged with sexual assault. Instead, he was charged with murder, and the court could have easily said that just because he didn't commit the sexual assault doesn't mean he didn't commit the murder. That has been the normal response from the Court in the past, which is one reason why I think this is a significant decision.
The Court's holding is limited, and it probably should be. The convction must be based on the perjured testimony - if it is only a part of the State's case, that is probably not going to be enough.
No matter how limited the holding may be, it is still a step forward for a Court that will never be accused of being defendant friendly. It's also a step forward because its a recognition that innocent people are convicted - something the Court has been reluctant to acknowledge in anything other than slam dunk DNA cases.
