It goes to the issue of authentication ... the more difficult it is to authenticate, the more open to question its validity and/or its content. Also, if it can be determined that it is a valid copy of the original document, it is still possible the contents are fabricated, or added long after the event, etc etc.
Agreed. Thinking about the hierarchy of validity:
We could have an original.
We could have a Medallion signature-certified notarization of some kind.
We could have a “vanilla” notary-certified copy.
We could have an ordinary Xerox copy.
We could have some document where somebody (an ordinary person, a person related to the beneficiary of the document; an FBI agent, a fiduciary) attests to the validity and genuineness of the document.
We could have something we picked up out of somebody’s desk who supposedly had something to do with the production of the referenced document.
We could have something fished out of the wastebasket next to somebody’s desk.
What we have here is essentially bottom-rung document authenticity, and it would be malpractice for any attorney representing the defense not to bring this up, with gusto.