I was reading an unpublished case from the Virginia Court of Appeals which dealt with the introduction of evidence "subject to cross." I don't know if this exists in other jurisdictions. I know I sure as heck didn't learn anything about it in law school.
Here's how it works: A party has a witness on the stand and moves some sort of evidence into the case (physical evidence, a written confession, a report, etc.). The other party doesn't state an objection but notes that this is "subject to cross." The judge then enters the item into evidence and the questioning of the witness continues. When the witness is passed and the second party does his cross examination. During this cross examination the second party can inquire as to things such as chain of custody, validity of a test, accuracy of a report, etc. If the second party establishes some sort of error that party then moves to strike the evidence from the record. If the judge agrees it is stricken.
I don't particularly care for this procedure. It should be of very limited use, only for items which have absolutely no other effect on the evidence or testimony of the witness or case. It should never be allowed in a jury trial. Still, it seems to be the default position in a number of courtrooms for wider evidence. I know that I have stood and asked the judge to voir dire a witness as to certain evidence and been told that the evidence was being entered subject to cross and that I could address it during cross examination. Of course, the difficulty is that once that barn door is opened a whole lot of cattle might get through before you can close it again. Imagine a report coming in and an expert basing 2/3 of his testimony on it before you can get it thrown out on cross.
Is this just a Virginia procedure or does it exist out there in the rest of the country as well?