Re: So electronic records are tainted evidence
It is, and always has been the case that virtually any digital file can be tampered with, however there are a number of balances in that.
1. Why would someone tamper with it?
2. How easy was it to undetectably tamper with in the first place?
3. How much would it cost to undetectably tamper with?
I would suggest that you would need to spend far more money tampering with digital evidence than it would actually be worth. Just think of all those little things you would need to change, undetectably.
Using media tools to massage media files is fairly easy to detect, and would render the use of those files meaningless, although there are legitimate reasons why you might, to enhance say, an Audio file. These can be used as evidence, provided that you retain the original and can show that your enhancement is independently repeatable, and legitimate through the chain of custody.
I'd expect it to happen with intelligence services, for very, very high value targets, but it's beyond the financial ability of normal Law Enforcement. I do wonder what you would have to do to undetectably alter a video or audio file, if it's even possible with some formats.