One issue is what the accused must do to secure confrontation. My answer is: If the defendant has to do much, beyond confirming that he wants confirmation, the opoprtunity is not adequate. In other words, it is not acceptable for the prosecutor to say, "We intend to use the statement of this witness at trial, because she may be unavailable. If you want to cross-examine her, take her deposition now." The accused has a right to be passive and "be confronted with" an adverse witness; it is not his responsibility to find the witness and compel her to testify. So the prosecution has to say, "If you want to cross-examine, just say so, and we'll arrange for her deposition." The accused does not have the right to demand that the witness be brought to his living room (or jail cell) for confrontation. I don't know of law on the subject, and would be curious to learn, but I suppose the accused, if at liberty, may be required to travel at his own expense within the jurisdiction for the deposition, and at the expense of the prosecution if the witness cannot be brought there but a deposition can be arranged elsewhere. (And counsel?)
A second issue that sometimes may arise is what kind of notice of a deposition is sufficient. Suppose the accused has been identified but not yet apprehended. Is it sufficient for the prosecution to give notice at the accused's last known address and to people who would expect to know his whereabouts? I would guess so; again, I am curious to know if there is law on the subject. (Whatever notice codified rules of criminal procedure require for a deposition is not necessarily the constitutional minimum requirement.) What if the accused has been identified only as the person who has a given DNA profile -- can adequate notice be given then? I doubt it.
Third is the question of whether the opportunity came so soon that it should be deemed inadequate. Defense counsel may argue, "Yes, the prosecution arranged a deposition, but I had just been appointed and even had I been as prepared as I could be at that point I would not have known nearly as much about the case as I do now." In some cases, I believe this argument will have force, and in others not. The judge should not simply accept an assertion of prejudice, but should ask, "Well, what is it that you would ask if you had the opportunity now?" (I am not sure that the proper baseline is what counsel would have been able to do at trial -- perhaps a somewhat less satisfactory opportunity for cross should still be considered sufficient -- but at least it is a plausible starting point.) In a complex case, in which the witness's testimony is closely tied to other evidence and ongoing investigation generates fuller understanding of the facts over time, defense counsel may well be able to persuade the court that the defendant is prejudiced by how early the opportunity for cross was offered. But, say, in the case of an expert witness who is prepared to testify that two samples, one found at the crime scene and one taken from the accused, had matching DNA, the argument would be hard to make successfully: Counsel does not need to know much about the case to understand her interest -- to undermine the prosecution expert's conclusion that the DNA profiles match -- or to do as effective a job as she is ever likely to do.
Fourth, there is the question of motivation. In California v. Green, 399 U.S. 149 (1970), the Supreme Court held that the accused's opportunity to examine a witness at a preliminary hearing suffices for purposes of the Confrontation Clause. I am dubious about that holding. I doubt if counsel really has the motivation at a preliminary hearing to cross-examine fully. On the other hand, if defense counsel takes seriously the injunction, "Well, you'd better have that motivation, because this may be your only opportunity for confrontaiton," then we may have much more time-consuming preliminary hearings and many extraneous examinations. I am very curious to know how defense lawyers in California and other states that have preliminary hearings tend to react to this situation. Interestingly, one Florida appellate court has taken a view substantially at variance from that of Green. In Lopez v. State, 888 So.2d 693 (1st Dist. 2004), the court held that a deposition taken for discovery -- as opposed to one taken for perpetuation of testimony -- does not qualify as an adequate opportunity for cross under Crawford. The statute allowing discovery depositions, said the court.
was designed to provide an opportunity for discovery, not an opportunity to engage in an adversarial testing of the evidence against the defendant. Nor is the rule customarily used for the purpose of cross-examination. Most good criminal defense lawyers attempt merely to learn what the testimony will be and, at the most, to limit the testimony.The court also quoted from a prior state supreme court decision that said:
To similar effect, the Colorado Supreme Court, acting directly in the teeth of Green, has held that a preliminary hearing does not give a sufficient motive for cross-examination. People v. Fry, 92 P.3d 970 (Col. 2004) ("the preliminary hearing is not intended to be a mini-trial . . . "; noting that usually, if probable cause is established, the defense has little motive to cross-examine).
Fifth, what limitations were imposed ont he ability to cross-examine at the prior proceeding? Fry, supra, has pointed out that at a preliminary hearing, where the question is whether there is probable cause, the judge is foreclosed in all but "exceptionally rare" cases from making credibility determinations. Accordingly, defense counsel is likely to be "curtailed" in cross-examination, because she has no legitimate grounds to establish the lack of credibility of the witnesses.
Finally -- at least the final issue I will address here -- there is a question of policy. Unlike Florida, the federal jurisdiction makes it very difficult to take a deposition of a witness in a criminal case, even for preservation of testimony; the standard under Fed. R. Crim. P. 15(a)(1) is that a motion for a deposition may be granted "because of exceptional circumstances and in the interest of justice." It seems to me that this is far too stringent; putting aside the question of discovery, a party ought to be allowed to take a deposition of a witness for purposes of preserving the witness's testimony merely by showing that the witness is friendly. (Producing an affidavit of the witness summarizing the testimony would generally do the job.) Prosecutors might decide not to take depositions in most cases, but that would be a decision they would make at their own risk.
A potentially sueful source of caselaw in this area is Francis M. Dougherty, Annotation, Admissibility Or Use In Criminal Trial Of Testimony Given At Preliminary Proceeding By Witness Not Available At Trial, 38 A.L.R.4th 378, §§ 6-7. (2004).