Posted By:
JKAl,
The way you could prove it with the goudey would be by the submission records and by the purchase records. Hypothethically lets say:
Buyer 1 - buys a psa 1 MK (records from REA or Ebay reflect this purchase)
Buyer 2 - has records showing he bought a PSA 2 (for example, a printout of the ebay page or notification that he won). Comparison of the marks on the physical card to the scan of the psa 1MK reveal its the same card.
It becomes fairly obvious that the alteration occurred between the purchase by buyer 1 and the sale to buyer 2.
On the otherhand, if buyer 2's records reflect that he bought a psa 1MK from buyer 1, and buyer 2 still owns the card, then its fairly easily provable that the alteration occured while the card was owned by buyer 2.