You assume legal framework will keep up to pace with technology with no lag.

I trust that, due to jurisprudence model, the legal framework will always have some lag[1] after game-changing technology becomes mainstream... sometimes this can be significant.

[1] disclaimer: active legislation efforts can move faster than tech - especially due to lobbying.

In theory it doesn't have to - there are already legal procedures for qualifying and admitting expert testimony at trial that work quite well (see http://en.wikipedia.org/wiki/Daubert_standard). So if you were in jeopardy primarily due to video evidence which you knew to be faked then you could bring a machine vision or CG expert into court to demonstrate the unreliability of the video evidence.

But this is not to say that our system for handling forensic evidence works great - it doesn't sadly, and part of the problem is that juries are often reduced to trying to weigh the credibility of competing expert testators without rigorous standards of measurement or terminology. You'll probably be interested in this: http://www8.nationalacademies.org/onpinews/newsitem.aspx?Rec...