No single mechanism makes a record tamper-evident on its own. It is the combination that does the work: a hash shows whether the file's bytes have changed since a specific moment; a timestamp anchors that moment to a documented time source; and a custody log shows every access, review, and export event that touched the item afterward. Remove any one layer and a gap opens: a hash without a custody log cannot show who had access to possibly re-hash a modified file; a timestamp without a hash cannot show whether the file itself changed after that date was recorded.
The practical discipline that keeps a file tamper-evident is separating the original capture from everything derived from it. If an item is annotated, cropped for presentation, translated, or summarized, that work happens in a new, clearly labeled layer, never by editing the original capture. The original stays frozen and hashed; every derivative points back to it. This is what lets a file survive a skeptical question like "how do we know this wasn't edited?" without depending on anyone's memory of what happened.
Tamper-evident is a property of the handling process, not a guarantee about the underlying online content's truth or authenticity. Finium's evidence files are built to be tamper-evident from capture through export; whether specific content is accurate, defamatory, or actionable remains a judgment for the law firm or qualified counsel reviewing the file.