[ErrantX]

In criminal cases I can see it often being necessary to within a day or two

Oh, if only. Digital evidence is seeing a lot more acceptance in recent years - but just recently there has been a sudden resistance to it, partly, I think, because of all the noise being made in the media about the ease of faking such things and the prevalence of viruses.

Oftentimes an audio recording tagged to within a couple of days will be fine.

But don't rely on that - it could easily be rejected out of hand by a judge who is not convinced.

Any sort of ambiguity in digital evidence and timestamps is being frowned on at the moment - at least here in the UK.