There's a fourth important thing, though: opportunity for cross-examination. The ability to ask the witness questions. And this has always been a big deal: even when you couldn't call witnesses of your own, or have a lawyer, or testify on your own behalf, you could at least ask questions of witnesses. That was pretty much your only right to defend yourself.
There are and have always been limits on the topics and extent of cross-examination, but it's a right that has pretty much always been there.
Now, at trial, she doesn't appear. But the court allows her testimony from the earlier hearing. Roberts challenges the admission of that testimony, for lack of confrontation.
The prosecution has to show:
How do we know if a statement is reliable? Well, in this case it was made under oath, in a court proceeding; there was a verbatim transcript; there was some limited cross-examination.
Why wasn't this just the former testimony exception? Because there was only pretty limited cross-examination-- the incentives to develop that testimony were different. Cross-examination is limited by statute at the preliminary hearing and also the battle isn't fully joined (they're just looking for probable cause).
Still, it was good enough, and the statements came in.
Note that by announcing this in a state court case, they're covering both state and federal cases: this is a strong rollout for this rule, then.
Juries decide reliability. The constitutional right is about confrontation, not reliability.
So now the rule is that the statement is admissible only if:
Crawford's wife invokes spousal privilege after previously giving some statements to police. Inadmissible because it's testimonial, and there was no prior opportunity for cross-examination.
This is a huge practical issue, but almost not at all in WI. Nearly every drunk driving lab has breath and blood test evidence from the state hygiene lab; most criminal cases have something from the crime lab.
In WI, by statute, you can offer a certified copy at the preliminary hearing (where there's no cross-examination). At trial, the analyst always appears (called by the state), unless the defense stipulates to the contents of the report. Lots of other states, for the sake of efficiency, just sent the reports as public records under seal (authenticated, good hearsay exception). But Crawford makes this practice unacceptable, even though it was way more convenient.