The bitcoin white paper says that spent transactions get pruned after being buried behind enough blocks:
- Reclaiming Disk Space
Once the latest transaction in a coin is buried under enough blocks, the spent transactions before it can be discarded to save disk space.
At some future point after a transaction gets pruned, couldn't the original recipient of that transaction then claim that she did not receive the correct amount of payment without worrying about anyone being able to disprove her because the transaction no longer exists in the blockchain?