Consequences of contradicting one&#39;s sworn testimony in separate cases? If a person makes a statement to police and 2 years later in a courtroom, under oath but not the same case, they make a statement that directly contradicts their witness statement does the defense have an obligation to inform the prosecution of that fact or can they use it in court to discredit the witness on the stand? (Assume that the contradiction will greatly benefit the defense and the witness is an important part of the prosecution's case.)
The defence in a criminal case has no obligation to inform the prosecution of anything. The onus is on the prosecution to provide the evidence to convict and the defence doesn't have to and indeed shouldn't help them do it. The defence can and probably would use conflicting statements by a prosecution witness to discredit that witness in the eyes of the jury. These do not have to be material to the case: just showing the witness is inconsistent in general is helpful.
Your main misunderstanding is that opposing counsel cannot testify. He can ask a question, such as "Did you say ...?", which provides Einstein an opportunity to answer in a way that maintains the credibility of his testimony, but consel cannot just enter his own testimony into the record. In addition, counsel on "his side" has the opportunity to pose appropriate clarifying questions, e.g. could ask "Did you repudiate that idea 88 years ago?", though there is a problem that the attorney may not have the technical expertise to recognize the subject-matter question that they should ask. Expert testimony does not attempt to determine the state of scholarship in an area, it attempts to resolve a specific factual matter. The two are not the same thing. Einstein would not testify as to what his general and special theories of relativity say, except in a bizarre universe where some person is accused of the crime of denying the theory of relativity. Instead, he might be testifying for the defense, where the defendant is accused of an act that (it turns out) is physically impossible in light of the theory of relativity. If Einstein had been in the habit of posing random mutually-contradictory conjectures on a weekly basis, opposing counsel's question could be relevant to establishing that the witness's testimony is not reliable. Theoretically, counsel could "hint" that the witness is scientifically flighty, so Einstein would have to have a credible explanation for changing his position. It is easy to demonstrate that scientists in general do change their positions as knowledge expands, so Einstein's burden would not be very substantial.
You will most likely be instructed to not share or even use your own translation of the testimony. In California, the instruction on translations is: Some testimony may be given in [insert name or description of language other than English]. An interpreter will provide a translation for you at the time that the testimony is given. You must rely on the translation provided by the interpreter, even if you understand the language spoken by the witness. Do not retranslate any testimony for other jurors. If you believe the court interpreter translated testimony incorrectly, let me know immediately by writing a note and giving it to the (clerk/bailiff). In People v. Cabrera 230 Cal.App.3d 300, it was ruled that supplying a competing translation is juror misconduct, see also People v. Marshall, 50 Cal. 3d 907 (it is misconduct for a juror to inject expertise into the deliberations, referring to the fact that a juror "informed the jury ... [that he had a] background in law enforcement, and that the lack of evidence did not mean the defendant has no criminal background, because juvenile records are automatically sealed at 18 years of age." Florida has a similar instruction: The evidence you are to consider is only that provided through the official court [interpreters] [translators]. Although some of you may know (language used), it is important that all jurors consider the same evidence. Therefore, you must accept the English [interpretation] [translation]. You must disregard any different meaning. If, however, during the testimony there is a question as to the accuracy of the English interpretation, you should bring this matter to my attention immediately by raising your hand. You should not ask your question or make any comment about the interpretation in the presence of the other jurors, or otherwise share your question or concern with any of them. I will take steps to see if your question can be answered and any discrepancy resolved. If, however, after such efforts a discrepancy remains, I emphasize that you must rely only upon the official English interpretation as provided by the court interpreter and disregard any other contrary interpretation.
One wouldn't be able to make a claim about a driving record without it being testimony. Testimony will be challenged during cross examination. The prosecutor won't be able to bring up prior bad acts (such as previous speeding tickets) but will most certainly be allowed to rebut any claim of no prior bad acts made by a defendant. When the defendant claims a spotless driving record the defendant is introducing character or a character trait into the trial. Once introduced by the defendant the prosecutor will be allowed to challenge the credibility of that statement and, therefore, the credibility of the witness. Imagine the following interaction: Defendant: I have a spotless driving record. Prosecutor: Are you saying you've never been issued a traffic ticket? Defendant: Um, Uh, well... When a defendant goes to court they are facing a specific charge. The prosecutor will present evidence that supports that charge and it is up to the defendant and his attorneys to sow reasonable doubt within the jury, or at least one juror. By presenting character, the defendant may appear to be saying either, "Hey, it was my first time let me off," or, "I've never done it before so I couldn't have done it this time." Either way, it probably won't create reasonable doubt in the juror's mind about the specific charge they're weighing and it has the potential to open a can of worms that would be unfavorable to the defendant.
There is, of course, no way to tell how the Court would deal with such a case today. This is not a frequently litigated issue, with lots of case law. I note that in the case you link to, the court limited the statute to false claims made "with a fraudulent purpose". This normally means that the claimant is attempting to secure an improper financial or materiel advantage. In the United States v. Tandaric case, the person convicted had falsely claimed to be a US Citizen on an employment application for a company which did not hire non-citizens, and so gained a job through this false statement. He could have been convicted of ordinary Fraud. The court has not been as protective of Fraud under the First Amendment as it has been of speech generally, or even of false but non-fraudulent speech. I am not at all sure if the court would overturn this law in a similar case today. Edit: In the United States v. Achtner case, the court wrote: But we agree with the District Court that the representation of citizenship must still be made to a person having some right to inquire or adequate reason for ascertaining a defendant's citizenship; it is not to be assumed that so severe a penalty is intended for words spoken as a mere boast or jest or to stop the prying of some busybody, ... This seems to dispose of the example in the question of a neighbor who is merly inquiring as to the character of the area, or perhaps from simple curiosity, and a false speaker who seems to get no direct benefit or advantage from the falsehood. Both linked cases involved false statements made to employers or potential employees, during wartime at that, with the false speaker's employment apparently at stake.
I have not found a case directly on point, but there is a case in the right neighborhood. In Flordia v. Carter 364 So. 2d 1249, Carter was charged with perjury for making a false statement under oath. He recanted his testimony in a letter to the defense attorney the next day. Subsequently he was charged with perjury: the trial judge dismissed the case based on his having recanted (which is a defense to perjury). The judge said (quoted in the appeal below and citing a relevant precedent Brannen v. Florida 114 So. 429) It matters not whether Carter knew his original testimony was false or whether he was merely mistaken. "The law encourages the correction of erroneous and even intentionally false statements on the part of a witness, and perjury will not be predicated upon such statements when the witness, before the submission of the case, fully corrects his testimony." The lower appeals court rejected the trial court's dismissal, saying Recantation is a defense to an allegation of perjury only where there is an acknowledgement of the falsity of the original sworn statement, a voluntary retraction of that statement, and a new statement which discloses the true facts. It is not a viable defense where the perjured testimony has substantially affected the proceeding or it has become manifest that such falsity has been or will be exposed. Otherwise, one could rest on his lie, allowing it to substantially affect a proceeding, and never retract unless the falsity had been exposed. This would provide no inducement or encouragement to tell the truth. That court basically felt it was based on the threat of being discovered, and felt that a particular state statute had taken away the recantation defense, so they reinstated the charge. The appeal to the Florida Supreme Court, Carter v. Florida 384 So. 2d 1255 basically declared that the appeals court was wrong about the statute (they officially held that recantation is a defense to perjury). They concluded that Carter gained nothing by recanting (that was a distinguishing feature in a precedent that the lower court favored). The dissent in this decision opined that It may be that the false deposition testimony by Dr. Carter was inadvertent and without criminal intent.... These, however, are factual issues and should be resolved by a jury rather than by the trial court on a motion to dismiss. What unifies all opinions on the matter is that a false statement made under oath must be recanted. The reason why Carter was not convicted was that he (possibly) was unaware that his testimony was false and he did recant when he became aware of the facts.
There are instances when the testimony may still be admitted. For example, a deposition may be admitted at trial either for impeaching or when a witness cannot attend, which involves the circumstance of death (FRCP 32(a)(4)(a)). Additionally, regarding hearsay, there are numerous exceptions. My Evidence professor said in class "If you cannot find a way to get evidence around a hearsay objection, you are not trying hard enough." One such hearsay exception states in the committee notes: Accordingly, the committee has amended rule 803(8) to refer to the provision of [proposed] rule 804(b)(5) [deleted], which allows the admission of such reports, records or other statements where the police officer or other law enforcement officer is unavailable because of death, then existing physical or mental illness or infirmity, or not being successfully subject to legal process.
I haven't found a recent case like this where it constitutes evidence. Military members didn't have an express right to remain silent until somewhere in the 1950s, so one chances are there might be cases prior to that point. The present right is codified in 10 U.S.C. 831, which is Article 31 of the UCMJ. That said, there is certainly a well documented adverse inference effect. While jurors aren't supposed to take the silence into account (e.g. when a defendant elects not to testify or exercises a right against self-incrimination), it's a difficult thing to do, practically speaking.